Based on RockinB's idea, I've created this new Dreamcast tool called VMZip.
The idea behind VMZip is simple but powerful: compress & decompress VMU save files using BZip2 compression, and save the result file on a target VMU.
For example: you have a Quake 3 Arena save that takes 25 blocks, but you don't want to erase it to have free blocks for another game save. You can use VMZip to compress the Q3A file, and the result will be a 3 blocks file. Now you've 22 free blocks, provided that you erase the original Q3A save and keep the compressed file.
Take a look at the screenshots here.
Dowload VMZip v1.0.0 unscrambled binary (.BIN), selfboot inducer (.SBI) and source code from my site or SourceForge.net
Controls: (A) selects, (B) cancel, (X) calculate compressed/decompressed file size, (Y) credits
post your comments!