There is buzz about how Jason Kottke, of kottke.org, has abandoned his experiment of micropayment donations to support his full-time blogging. He pulled in $40,000 in the year, almost all of it during his 3 week pledge drive, but that's hardly enough. Now I think he should try adsense, but I doubt he hasn't heard that suggestion before.
However, PBS/NPR are able to get a large part of their budgets through pledge drives, so it's possible to make this happen. I think we should be able to do it better on the web.