The gzip Recovery Toolkit attempts to automate the recovery of data from corrupted gzip files (including tarballs) through a program called gzrecover. This package is still very experimental at this point.
ImageOptim decreases the file size of PNG, JPEG, and GIF images, even those "Saved for Web". It combines OptiPNG, PNGCrush, AdvanceComp, PNGOUT, Jpegoptim + Jpegtran, and Gifsicle for the best possible optimization.