The Zip lets your Zip or Unzip any file using the iPhone. This simple and stable App can be really handy. For zipping files just enter the target directory of where you want save the zip file followed by the location of the files you want to Zip (in the first box). For example: /cool.zip /cool.mp3 & hit the Zap key!.
For unzipping files enter the location of the compressed file in the second box and then press the Zap! button. Eg. /cool.zip
Cydia is an Installer alternative, that Installs on Jailbroken iPhone 2.x… Info here