Since you mentioned donations, I figured I'd ask you this. I've got a site I'm working on that I want to commit to full time, potentially without any other source of income. When you say it was "enough to keep the site running", do you mean enough to maintain servers, or enough to maintain your refridgerator and roof as well?
Also, is it ok to have a donation based site if you eventually hope to profit significantly from it? Or does that tend to imply that it's a "community" or "non-profit" sort of thing they're putting money towards?
By "keep the site running" I mean it paid to keep the server hosted at a local ISP. (Good Lord, what a blast from the past; it was the last server I ever actually physically saw, a used SPARCstation running Solaris, and I carried it to the ISP myself.) Occasionally, I had enough in the kitty to pay some personal bills. That was just on PayPal donations from one link in the corner of the home page.
But I wasn't even close to being committed to Despammed full time (although it sometimes felt like it during my trial-by-fire sysadminning lessons when things went wrong) - so I don't think there's much to generalize from. You have the advantage of full attention - but I was the only free spam filter in the world for a short time, and a few people were pretty virulently thankful about it.
As to the morality of donations when you hope to profit later - absolutely. You're not forcing people to donate, and if they like your site well enough to give you money, they will not only cheer you on if you become profitable, they'll even feel personal pride that they helped you on your way. The Knew-Him-When effect. I think only a few people would feel you'd sold out. And you can ignore them; they'll be looking for a way to feel superior no matter what, so you might as well let them feel superior all the way to your bank. Everybody's happy.
Now if you actually sell yourself as a community effort, then appropriate it to yourself when it's time to make money, that will piss people off, and rightly so. It's really all your attitude, though, that sets the tone. If you're honest about your plans, that's all people want.
Also, is it ok to have a donation based site if you eventually hope to profit significantly from it? Or does that tend to imply that it's a "community" or "non-profit" sort of thing they're putting money towards?