That's such a brilliant idea. What if there was a website where people could divide up which OSS projects their $1k or 1% goes to? It could be anonymous, pseudonymous, or public, depending on how bold the philanthropist was.
To summarize: before beginning I'd like to find similar systems ('competition'), how to locate recipients, and how to move the money around without losing any of it to fees, ideally. The marketing angle is easy: 6-figure devs might like the idea of giving in this way. Your basket could even be a sharable point of pride.
You'd almost always want it to go to appropriate foundations (501(c)3 or equivalent), not individuals, except when supporting projects that really only have a single developer and no organization behind them. That also makes it easier for companies and individuals to give, since they can deduct it from their taxes.
But this brings up a few interesting points. First, if you give only to the founder, and not the contributor, will this engender resentment? Second, ideally the result would be that the founder would work more on the project in a consistent way, but that sort of gift would need to be something more along the lines of a stipend over the course of a year or two. Third, if the amounts were large enough (which would be the case if every 6-figure dev gave $1k/year), you could do something along the lines of the MacArthur foundation so-called "genius grants".