recently spent quite a bit of time re-organising and tagging my del.icio.us bookmarks and quickly realised that I'd forgotten about a lot of really useful links I'd bookmarked. I really like StumbleUpon - clicking the Stumble button takes you to a random
Here are the top 20 largest social bookmarking sites ranked by a combination of Compete and Quantcast data. For each site, we show unique U.S. monthly visitor data as well as respective rank.