The 160 Gig version of apple's iPod is the biggest iPod you are going to find, in regards to its size, as well as its storage capacity.
(40,000 songs) Silver, Black Up to 40 hours of music playback; up to 7 hours of video playback
2.5-inch (diagonal) color LCD with LED backlight
Dock connector, stereo minijack
USB through dock connector; component and composite video through dock connector (with AV cables or kit, sold separately); audio through headphone jack
About 4 hours (2-hour fast charge to 80% capacity)