What are some alternatives?
Lepton - Lepton image compression: saving 22% losslessly from images at 15MB/s
Transmit - Transmit is an FTP client for Mac OS X and Mac OS Classic (which is unsupported).
File Converter - Convert & compress everything in 2 clicks!
CodeKit - CodeKit allows you to optimize the performance of your website by automatically and efficiently compiling a variety of popular languages.
TotalTerminal - TotalTerminal is a plugin for Terminal. app which provides Quake-style terminal window available on keyboard shortcut.
PNGGauntlet - -Combines PNGOUT, OptiPNG, and DeflOpt to create the smallest PNGs