The big social bookmarking sites are Delicious, Digg, Stumbleupon and reddit. This is my 9005th entry, and I learnt about 5000 entries ago that you can't predict which entries will gain traction with these social bookmarking services.
Stumbleupon is currently sending a whack of traffic to my Best. Party. Playlist. Ever. entry. It's just a laundry list of the songs I played during a corporate retreat at Horseshoe Valley ski resort. The entry is six months old, and certainly not one of my more inspired posts, but it got added to Stumbleupon five days ago and is still gaining momentum. You just never know...
I gave up trying to predict which entries might cause a stir with social bookmarking sites, and so should you.