Managing Player Owned Stations (POS towers) can be a fun challenge. Most of the playerbase of EvE would most likely consider me not right in the head, or at the very least a sadist, but I actually find enjoyment in the activity.
There are a multitude of purposes and reasons for anchoring a POS tower in space, but my favorites by far are the moon-reaction towers. I think that this comes from my "collectionitivism" (I just made that up) mentality where I really enjoy acquiring and collecting items, even if they are just numbers on a screen or pixels in a game, and these mining/reaction towers are a great way to satiate this semi-passively.
There can also be a surprising amount of profit to be had in running moon-reaction POSs. There are of course the well known and highly coveted/"profitable" R64 and R32 type of moons. These will make you a tidy profit in just the raw moon-goo. These types of moons are usually claimed under "eminent-domain" terms by whatever large alliance or coalition owns the space that you happen to find yourself living in. In my experience: even the R16 and R8 type of moons are usually given out to individual corporations to hold and manage.
This unfortunately leaves the aspiring POS Mogul in a tight spot if he is wanting to run any towers for his own profit. Fortunately there are still a few options left to them. If they are proficient at running operations, demonstrate the interest, and their corp/alliance leadership trusts them; the most efficient use of their time would be to try and get a position managing the corporate towers. This, if done right, can net both the corporation and the player a tidy sum of ISK. (Be sure to negotiate your fees up-front) However, fear not as there are still a few options left open for those who cannot get the responsibility to do this.
Most people do not even look at the R0 moons. All of their raw products are pretty much worthless and even the product of their simple reactions are most likely cheaper on the market than the comparable fuel costs for the towers. However there are a few that are worth doing: Namely the Silicon Diborite and the Ceramic Powder. These both consume Evaporite Deposits and Silicon, which are the two most common elements in the galaxy aside from stupidity and Stealth Bombers. You cannot help but stumble over moons containing at least these two gasses. These are both simple reactions as well, meaning that you can use a Caldari Medium tower to do this entire reaction with enough CPU left over to hang a Personal and a corporate hanger with a Ship hanger off to the side. Now you have both a money-making tower and a Safe-POS for ratting or mining or whatever. I saw money making because with those two reactions you should turn a profit even after accounting for fuel costs for a month's operation. I am talking numbers on the order of 50M ISK for Ceramic Powders and 150M ISK for Silicon Diborite. Now, 150M a month in profits after fuel and precursors is actually a nice profit margin. Actually, for a few months there (September and October) this reaction was the most efficiently-profitable ones of all the reaction schemes, simple and complex both.
Profit-Efficiency is a very helpful way to evaluate the feasibility of these towers. Most players would be content with evaluating the simple comparison of units produced against the Jita-price for each. The more discerning players will know that they should subtract the fuel costs of the tower from that number to ensure that they are making a profit. However those in the know will realize that they also need to subtract the raw value of the precursors from their Net Income number in order to get the actual Profit that they will be receiving. I took some time when I started my Corp-level POS-Reaction manager position and created a spreadsheet that auto-calculated all these values using auto-scraped market data from Eve-Central and I was quite surprised at the number of reactions that were actually selling on the market for less than the value of the raw ingredients. I am not sure how these people are making a profit, perhaps they know something that I do not, but nevertheless there their market orders are in Jita.
Ok, so I have all these towers sitting in space and making money, now what? Well this can become quite a chore.
All of the towers need to be constantly fueled, need constant raw-material feeding for the more complex reactions, and likewise emptying of the reaction silos. Moon goo and their reaction products are also quite bulky, and this makes the logistics side of things complicated. This isn't even counting the Herculean effort of procuring the racial Fuel Blocks in the first place. Yeah you can try and find a local source of your fuel, but even then it is not a trivial task to mine up and manufacture all the fuel that even a moderately sized reaction network requires.
Most POS managers make it a priority to train up the skills needed for either a jump freighter or a Rorqual to increase the ease of caring for their towers. Newer players, or those who are just too broke to afford such an investment, are relegated to T1 transport ships if they are lucky, or Blockade Runners if they are unlucky due to living in hostile space. No one in their right mind would use an Orca or a frieghter to do this work as they are way too vulnerable to being caught and destroyed by hostiles. With the recently completed Transport Ships rebalance released in Odessey this task is no longer a nightmare if you don't have Gallente Industrial Ships V trained as each race now has a T1 ship that can hold approximately 38,000 m3. With Silos having a maximum capacity of 20,000 m3 this means that you can go out and fuel and feed a single large reaction tower in a single trip. You cannot completely fill it to capacity from empty, but after the first filling you can keep it constantly running with minimal effort.
Using these T1 transports is still a risky business so adequate measures are required to ensure that you are not featured as a ALOD for people to point at laugh at. Often times you will find yourself flying around with 250-350M worth of goo or reactions in a ship that barely pushes 3k EHP. These loot-pinatias are pretty much kill-mails waiting to happen if some hostile happens across your path. This is why the Prime Directive of null-sec life is so important. ALWAYS READ AND PAY ATTENTION TO YOUR INTEL CHANNELS. It is also extremely valuable to have a scout. By enlisting the aid of a new-bro corp-member, or even an alt, flying a noob ship with a MWD you can send him first through gates and jump bridges to see what is waiting for you on the other side. 99% of the time he will only find empty space, but that 1% chance that there is someone waiting for you on the other side is enough to make you break out in a cold sweat.
T1 transports are also much quicker than the larger industrial ships. It is entirely feasible to throw a 10MN MWD/AB and a cloaking device on your Bestower or Tayra and successfully evade a hostile sitting on the other side of the gate. This method doesn't always work, but it has saved my bacon enough times that I always fit them regardless. Multi-spectrum target-breakers are also a very handy mid-slot module to have, but not rely on them. If you ever find yourself having to activate one always do it at maximum align velocity and consider playing the IRL Lottery if you manage to escape because you used it.
Most importantly, having the keys to the POS towers to run the moon-reactions can be very beneficial financially. This is a job that isn't for the lazy or the uninterested. If you find yourself in the unfortunate position that you are the only, or the main, individual feeding and taking care of your corp's reaction network; then you are entirely justified in making off with all the unsold goo and reactions if things go south. I have recently found myself in this position with my prior corporation. I had designed, purchased, anchored, and tended to the 9-tower reaction chain out in Fountain for about two months. Sadly, due to other IRL and IG reasons, my corporation has fallen to pieces and I was able to score pretty much everything in the Reactions hanger and all the hardware hanging in space. It is going to be an interesting challenge getting all these items out of the region and back to Jita for liquidation; but ~3.8 bn for two month's work isn't that shabby in my books. It probably isn't quite up to the ISK/h that PLEX runners make, or even the station-trading that make Gevlon Goblin rich; but it is enough for my purposes.