Not quite MSC easy, but
SharePod is a small Win32 program you dump onto an iPod and run off of the iPod that lets you upload and download songs into the iPod database without using iTunes.
Personally, I went with
rockbox on my nano, which does ReplayGain, Ogg, and songs are added like Mark is talking about.
No matter what, it's a real pain to use both iTunes and some other way to manage/upload/download stuff from an iPod; either drink the kool-aid or don't drink the kool-aid, it's not worth trying to drink the kool-aid and the 18 year old single malt.
--Nathan