FreeSoftwareTools.net

Peazip is an open source file and archive manager. It is flexibe, portable, secure, and free.

Can pack and unpack : 7Z, ARC/WRC, BZ2/TBZ2, custom, GZ/TGZ, PAQ/LPAQ, PEA, QUAD/BALZ, split, TAR, UPX, ZIP
Can unpack : ACE, ARJ, CAB, CHM, COMPOUND (MSI, DOC, XLS, PPT), CPIO, ISO, Java (JAR, EAR, WAR), Linux (DEB, PET/PUP, RPM, SLP), LHA/LZH, LZMA, Mac (DMG/HFS), NSIS, Open Office files, PAK/PK3/PK4, RAR, SMZIP, U3P, UDF, VHD, WIM, XAR, XPI, XZ, Z/TZ

Peazip is extremely useful since it can unpack ACE files and supports the PAQ format.
PAQ format, especially the PAQ8px is the best compression algorithm, you can see the overall results here.
With Pezip you can create encrypted 7Z & ZIP files using the AES algorithm (Rijndael).