Archiving program that adds redundancy

I'm looking for a archiving program that adds redundancy to an archive. Example : I've got 500MB of data, and a 700MB media to burn it. Rather than waste 200MB, I want to use them to add redundancy. Then if some data is damaged, the archiving program will be able to restore it because it were redundant. Does such a program exists ? Which one would you recommend ? If possible, a FOSS software: if you don't have the archiver source code, you don't know if you'll be able to extract the archive in the future.