Henry Copeland, who runs the blogads system, has a post up about blogs and the '04 election. I think he's right that there's an opening for a few candidates - one or two Senate candidates and a few House candidates - to tap into blogs and the internet the way Dean has done and help create both a buzz and increase their fundraising abilities.
It isn't that buying a blogad is the necessary way to do this, or the us bloggers are bought for a few bucks, but advertising on blogs helps get the attention of both the blogger and the readers.
My own plan has been at some point this year to "adopt a candidate" for a House race. Ideally, this would be someone with a reasonable chance of beating a Republican incumbent, particularly one who is a real tool. Secondary considerations would be someone who was relatively local to me, though that isn't necessary. My own Rep is in a completely safe seat so that isn't really an option. Anyway, I'd try and help do a bit of fundraising and steer people for volunteering.