For a trial basis I’ve added Politigg buttons on my blog posts. Although I have a ShareThis hoojamaflip at the bottom of my posts from which you can use any standard social bookmarking website, it doesn’t appear to generate much usage and the appeal of Politigg is that is specifically focuses on politics, which is my field (I’ll add a “geekigg” button as well should one become available).
The problem I have with all these social bookmarking websites is that there are so many of them. With no gold standard, it gets a bit frenetic. So whether I stick with Politigg depends entirely on whether others do the same.
UPDATE: One thing I should add though is that I am intrigued that under ‘political parties’ Politigg offers you the choice of the Libertarian Party and the English Democrats, but not the SWP, Respect or any other established hard left party (no NI parties either). So it is clear where the developers are coming from!