Linux: Whether it's a troublesome hard drive or an old DVD that's spitting out I/O errors, Safecopy is a Linux utility that will keep trying to recover data until it gets to the end of the media. Where other tools give up and force you to start the recovery process again, Safecopy presses on through errors, resorting to low-level read and copy operations if necessary.
If you've ever run a drive recovery tool and had it fail against a hard drive with a bad sector, you know the problem that Safecopy is trying to fix. The app requires Linux, so it's a perfect fit if you want to build custom live CD and other sorts of hackery. Aside from being so powerful, Safecopy works on virtually any type of media: hard drives, CDs, DVDs, and even tape drives and enterprise storage tools.
Safecopy is completely free and completely open source. Give it a whirl the next time you have a drive that nothing else can recover, and let us know what you think.