JFileRecovery

Have you been copying data from cd's or dvd's and found you have a disc that is too scratched to recover your data back from? You get this "cyclic redundancy error" message from your computer and the copy process aborts, leaving you without a copy of the file in question. It's pretty horrifying, especially if it's something very important or valuable. Well this program fixes the main error you get when you have this problem "cyclic redundancy error", allowing you to copy most if not all of the file, usually providing you with a usable copy.

From their site:
JFileRecovery is a free Java Web Start application that can copy files from damaged storage devices and media, skipping over problematic regions that typically cause copying to fail. If the file is listed, there is a good chance that JFileRecovery can salvage much of the data with minimal corruption. For many media files such as MP3, MPEG, AVI and JPEG, corruption is often not even noticeable. Copying large video files from scratched CDs and DVDs often results in CRC errors, aborting the process and making transferring the file impossible. JFileRecovery can bypass these CRC errors, with minimal data loss which may only be noticeable as a single bad frame in the video.
How Recovery works: JFileRecovery is not based on low level disk reading but on the observation that damaged areas take longer to read. The multi-threaded design of JFileRecovery makes it possible to abort reads from slow responding regions and continue the copy process. Additional attempts at recovering bad regions can be made as required.
JFileRecovery was developed to recover large video files from CDRs with scratched top surfaces. Blocks of 1KB in size are not noticeable in most video files unless they occur at the very beginning or end of the file.

Warning

JFileRecovery should not be used to recover executable files. A single error in an executable file is very serious and could potentially damage your computer.

This program requires Java to run.