A sick hit that's been circling the intertubes from a Division III game last week:
Great hit, but this is the best college one I've ever seen - Quentin Coryatt destroying a TCU split end.
I have an alternate angle .gif for some reason.
The best pro hit ever is Steve Largent venging on Mike Harden, but I have never seen video of it online. Let me know in comments or e-mail if you have any leads.