Actually 7zip only does
* Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR
* Unpacking only: RAR, CAB, ISO, ARJ, LZH, CHM, Z, CPIO, RPM, DEB and NSIS
But I agree that it is an excellent compression format. However its not great for working with "just about anything"
Winrar is definitely better than winzip, but again is hindered by a narrow range of compatability.
* GZ and TAR.GZ
* BZ2 and TAR.BZ2
* JAR (Java Archive)
* ISO (ISO9660 - CD image)
* Z (Unix compress)
To my knowledge izarc is the most versatile. Its free, and does
7-ZIP, A, ACE, ARC, ARJ, B64, BH, BIN, BZ2, BZA, C2D, CAB, CDI, CPIO, DEB, ENC, GCA, GZ, GZA, HA, IMG, ISO, JAR, LHA, LIB, LZH, MDF, MBF, MIM, NRG, PAK, PDI, PK3, RAR, RPM, TAR, TAZ, TBZ, TGZ, TZ, UUE, WAR, XXE, YZ1, Z, ZIP, ZOO.