Lyle's write up is quite good.
Here's the vid I did on them:
Mark Rippetoe has some excellent videos over on crossfit too. I posted them around here at one point in time... I'm sure if you do a search for the word "rippetoe" and posts made by me, they'll turn up.
With those three sources, you shouldn't have to look anywhere else.
And it would be cool if this forum were like others I belong to where people would actually film themselves performing particular exercises so form could be critiqued and corrected. I know on my forum this is something I will be pushing for.