Blogitive and similar sites let you earn money by making blog entries for advertisers. I’ve never tried this but it does look interesting, so any hints/tips, do’s/don’ts, recommendations, general comments etc would be greatly appreciated. From a quick scout around though, there seem to be mixed opinions about making money this way (i.e. is this just another form of spam!)
For a list of similar companies check out supermom’s page (a page or so down.) There are loads of other web-based money making systems/ideas etc, as well.