I've been "professionally" publishing RPG products for about two years now. And by that I mean that people pay money for them, not that it's my day job. The OSR/Indie scene is a weird sort of limbo for the semi-pro. It may the whole RPG "industry" is like this, but I wouldn't know. On the one hand, I definitely feel that my adventure writing –and my writing skills in general– have been pushed up a notch since Faster Monkey kicked off. The standard to which I need to hold what I put out there with a price tag on it is much higher than some crawl I might just chuck on the table for a Monday night game. It is also gratifying (and ego-stroking) to see people actually plunk down a couple dollars for something with my name on it, not to mention any favorable reviews that might crop up. The incremental boost to "geek cred" is nice too.
On the other hand, it truly is a labor of love in that what we do at FMG would never actually support anyone as a full time income, let alone the three of us that are involved. Faster Monkey pays for itself, and gives us a few dollars to spend, but it is miles from paying us for the time we spend on getting a product out the door.
Another "occupational hazard" of the semi-pro status is that –much like GMing instead of just playing– it can color your gaming experiences in general. Sometimes it's hard to justify time and energy spent on gaming when they aren't directly related to "work." Also, what might be a cool idea for an adventure might be passed over for something else because properly developing it into a product would be too difficult, or wouldn't have as broad an appeal as something more straightforward.
I say all this not to complain, but because I've had a few people ask me about publishing modules, etc. over the last several months and what's involved. While this isn't a complete explanation, I thought I'd share a few thoughts about it in general.