pngquant is a batch conversion utility to quantize and dither truecolor PNG images, especially those with a full alpha channel, down to "RGBA-palette" PNGs (i.e., PLTE + tRNS in PNG parlance). Such images are usually two to four times smaller than the full 32-bit versions, and partial transparency is preserved quite nicely. This makes pngquant especially useful both for Web sites and for PlayStation 2 development, where one of the texture formats is RGBA-palette-based (though not PNG-compressed).
The pnmtopng package contains the official pnmtopng and pngtopnm utilities for use with the rest of the PBMplus/NetPBM suite. They are among the best PNG-supporting applications available, with automatic detection of grayscale or palette images and excellent heuristics for creating the smallest possible PNG images.
UnZip will list, test, or extract files from a ZIP archive, commonly found on DOS and Windows systems. A companion program, Zip, creates ZIP archives; both are part of the Info-ZIP project. Both programs are compatible with archives created by PKWARE's PKZIP or Nico Mak's WinZip, but in many cases the program options or default behaviors differ.
Zip is a compression and file packaging utility for Unix, VMS, DOS, OS/2, Windows 9x/NT, Amiga, Atari, Macintosh, BeOS, SMS/QDOS, MVS, VM/CMS, and others. It is analogous to a combination of the Unix commands tar(1) and compress(1) and is compatible with PKWARE's PKZIP and Nico Mak's WinZip. It's part of the Info-ZIP project.
Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh). It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh.
GeoToad is a geocaching query tool to help speed up the boring part of geocaching: choosing the cache and collecting the data. It allows you to generate any kind of complex query you want, and the program will go and poll the Geocaching query, grab the data, and output it to any format you want. The Geocache info can be synced straight to your GPS, iPod, PDA, or cell phone in over 20 different formats.