makeself is a small shell script that generates a self-extractable compressed TAR archive from a directory. The resulting file appears as a shell script, and can be launched as is. The archive will then uncompress itself to a temporary directory and an arbitrary command will be executed (for example, an installation script). This is pretty similar to archives generated with WinZip Self-Extractor in the Windows world.
mkCDrec (Make CD-ROM Recovery) makes a bootable (El Torito) disaster recovery image, including backups of the Linux system to one or more CD-ROM(s) (multi-volume sets). Otherwise, the backups can be stored on another disk, NFS/CIFS disk, or (remote) tape. After a disk crash or system intrusion, the system can be booted from the CD-ROM and one can restore the complete system as it was. It also features disk cloning, which allows one to restore a disk to another disk (the destination disk does not have to be of the same size, as it calculates the partition layout itself). Currently, ext2, ext3, minix, MS-DOS, FAT, VFAT, Reiserfs, XFS, and JFS filesystems are supported. It can restore disks in Software RAID and LVM mode. It supports the One Button Disaster Recovery (OBDR) mode, which simulates a bootable CD-ROM on tape.
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).
UPX is a portable, extendable, high-performance executable packer for several different executable formats. It achieves an excellent compression ratio and offers very fast decompression. Your executables suffer no memory overhead or other drawbacks. UPX supports vmlinuz/386, linux/elf386, linux/386, win32/pe, dos/exe, djgpp2/coff, and many more.
hdup is used to back up a filesystem. Features include encryption of the archive (mcrypt/GnuPG), compression of the archive (bzip2/gzip/lzop/none), the ability to transfer the archive to a remote host or restoring from a remote host (with SSH), the ability to split up archives, and no obscure archive format (it is a normal compressed tar file).
ZZIPlib provides read access on ZIP-archives. The library uses only the patent-free compression-algorithms supported by zlib. Functions are provided that transparently access files being either real files or zipped files, both with the same filepath. The zip-archive can be used in the place of a normal subdirectory. It is written in portable C.