Amusingly I'm in a very similar boat to you. I'm fairly certain that almost all the money that I'm receiving on Gittip is due to my work on jQuery - which I haven't actively worked in quite a few years.
One way in which Chad explained it to me, that resonated, was that Gittip can be better thought of as a "genius grant". People are giving you money not to support a specific thing (otherwise Gittip would be project-centric, not person-centric) but to support YOU and the things you want to do.
It's kind of crazy because I'm fairly certain that I'm getting donations because of my work on jQuery and not for my current side-project research into Japanese woodblock printing - but people don't seem to mind! (And I've made it clear on my profile what it is, exactly, that I'm working on right now and what I'm using the money for.)
I have a full-time job at Khan Academy and I'm well paid so I don't need the extra money - but it is appreciated. I'm re-donating a portion of the money that I get. Additionally it's paying for my extra server costs for my side projects and it's probably even paying for a good chunk of my monthly utility bill. I've been trying to think of other ways in which I can use the money that'll have a more obvious "money in -> using money -> output" pipeline but I'm not sure what that is, yet.
Let's hope you'll be able to keep your account open and find good uses for the money!