I feel exactly the same (with ~300 forks, ~3000 stars - not that it means anything). It's a creative urge, like writing music (which I also do, and I feel the passion for both is very similar).

I've received some donations, but nothing that could pay for anything significant, but I don't really see the donations as something that might eventually pay, but instead I see them as "thank you for the work", which is always appreciated.

However, I have seen some upsides, which are hard to put a dollar value on:

* Found staff for my company

* Been asked to be a technical proofer on a Manning book

* Made great connections with smart people

* A powerful sense that I'm contributing to humanity (even if it's in a relatively small way), rather than just being a consumer

There are probably other things that I've forgotten, but there's more value to OSS than just cash.