I'm going to create an automated social bookmarker. Very likely it'll be a hosted web service that will just require a url, tags, title, description and will auto post them. Script will be hosted, but will be free to use for others to bookmark their stuff.

Only thing is I'm looking for a good list of social networks that are DoFollow but don't use captcha during the submission process. I already have a few, some are going to be a real challenge to do while others look really easy. I just wanted to get a good list of at least 25-30 before I start.

It's a bit of a recreational project, but I could see it being really handy when marketing landing pages, etc.

Well, The problem is that many of these sites are changing to NoFollow lately. What page rank must the sites have?