iArchiver is an archive tool that supports many
formats that Apple forgot. It creates DMG, 7-zip,
Zip, gzip, bzip2, and many other file formats in
three easy steps. It can also convert between file
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.