I have seen another service at Steffens Blog
The explanation on the TwisterMC site is quite good:
Everyone’s doing it; sharing their bookmarks with the world. Not only is it convent to have all your bookmarks available in one spot, but it also gives your site more exposure.
To help others easily social bookmark your page, I’ve put together a little code that will make it easy for you to add social bookmark links to your blog posts.”