As with any project like this, that last 20% completeness takes the most effort, and spending a couple of hours a week on it just won't be enough to take it to success. Building the product is just the first step, getting people using it and iterating is what matters to me.
I'm working with a startup now (Heyzap, YC W09), so that's where all my energy is being directed!
Why didn't you try finding a co-founder, and giving up the code in exchange for a portion of the equity. Giving it completely away just seems wasteful.
10-20% would guarantee decent payout in case the site becomes a success. You pretty much did all the hard work already, might as well ensure that you get rewarded for it eventually.
I'm working with a startup now (Heyzap, YC W09), so that's where all my energy is being directed!