Derek Wyatt’s Screencasts – By far the best series on learning Vim I’ve seen. Must see.
UPDATE – Derek Wyatt has created a new, more organized site for his Vim tutorials
Vimcasts – This is a good link to add to your rss reader. Updates fairly often with good vim tips.
Codeulate Screencasts’ Vim for Rails Developers – I actually haven’t gotten to watch this yet but I will be getting it soon.