One such service is bloggerwave. It's a paid post service based in Europe that connects bloggers with opportunities from advertisers. The advertisers pay for ads, the bloggers provide. What's great about this service is that you can take whatever opportunity you wish, so you don't have to worry about endorsing something you don't like or approve of. That's the danger with embedded ads; I can't tell you how many times I've visited a site in which the ads were directly opposed to the content of the site. Paid post services leave some power to the blogger, which is how it should be.