PeaZip is an open source file and archive manager for 32 and 64 bit Windows (9x, 2000, XP, Vista) and Linux.
For both platforms it is available as installable or portable package, not needing installation.

Full support: 7Z, 7Z-sfx, ARC/WRC, BZ2/TBZ2, GZ/TGZ, PAQ/LPAQ, PEA, QUAD, split, TAR, UPX, ZIP.

Open, browse, extract, test: ACE, ARJ, CAB, CHM, COMPOUND (MSI, DOC, XLS, PPT), CPIO, ISO, Java (JAR, EAR, WAR), Linux (DEB, PET/PUP, RPM, SLP), LHA/LZH, LZMA, NSIS, OOo, PAK/PK3/PK4, RAR, SMZIP, U3P, WIM, XPI, Z/TZ.

Other features: robust file copy, split/join files, quick or secure file deletion, byte to byte compare files, checksum/hash files, system benchmark, generate random passwords and keyfiles.

PeaZip allows to: browse files and archives (with multiple inclusion and exclusion filters), create/extract multiple archives at once, save archive's layout, save job definition as command line (to be inspected, or used in scripts), save job logs.
The user interface is skinnable for colors, transparence and icons.