This article focuses on iPod managing software. i.e. software that permits the transferring of content between an iPod and a computer or vice versa.
iTunes is the official iPod managing software, but 3rd parties have created alternatives to work around restrictions in iTunes. e.g. transferring content from an iPod to a computer is restricted by iTunes.
iPod syncing and maintenance features
Note 2: gtkpod developers have found a workaround [1].
Note 3: As of Version 3.02 [2].
Note 4: Support arrived with libgpod >= 0.7.90 due to the use of libimobiledevice.
References
Comparison of iPod managers Wikipedia(Text) CC BY-SA