I don't get why gittip lets me donate "per week" but not a one-time thing. I don't do recurring donations, especially something as often as per week - could totally see myself forgetting about it before the next week.
Well, there's plenty of one-time options (PayPal, Kickstarter, Pledgie, ...). Gittip is differentiating on the recurring option.
The goal with Gittip is for people to make a living on it. Bills are recurring, so funding has to be as well. Yes it means that there is some short-term money left on the table, but it also means that the money that is there is relatively stable and predictable over time. Gittip is designed to grow slowly and shrink slowly. The goal is for JSFiddle to be able to truly depend on it.
And the minimum tip amount is $0.25 per week, which is $13 per year: not that much. Note that the minimum charge is $10 (to minimize transaction fees). So if you only tip a quarter we'd charge you $10 every 37 weeks or so.
That said, I expect we'll mix in one-time payments in some form at some point. I've added a +1 for you here:
