I have been browsing through the social networking forum here and found a site called Voonee.com are links on their dofollow?
It appears to be dofollow, you should download something like SEOQuake so that you can see which links are nofollow/dofollow.
if you need to know if a site is dofollow or not, download the seoquake toolbar just hit the nofollows highlighter which will pretty much let you know if it is or not
I have checked it. It's a dofollow social networking site. It looks like Twitter but links are in dofollow.
Yup, nodofollow addon for Firefox works well. Posterous actually allows you to autopost to a ton of other social networks, some of which I believe are dofollow. Pretty useful for creating a link wheel, I've tried it with some (albeit limited) success. Definitely a timesaver though.