It ain't free, but it works pretty well:
File Scavenger
You can download a free trial version which won't recover, but will show what it thinks are recoverable files. You can make up your mind from there whether its worth takin' a shot at.
Another, with a trial version that will recover files up to 64KB is
Active Undelete
For larger files, you'll hafta pay for the full version.
I've used both of these - they have their quirks and limitations, but they seem to me to be among the better recovery utilities out there. There are plenty of others - you might wanna google up some reviews for file recovery applications.