So many complain about having too little battery life, so I decided to post a thread about usb battery packs. Some players such as the Sandisk Clip+, Fuze, and Clip Zip will play while charging with a usb battery pack.
For versatility, I like the $20 Tekkeon mp1580. It uses 4 nimh AA batteries(not included), so one can carry extra sets.
A more compact lighter choice that holds more power is the $30 Veho Pebble XT. It has a built in Lion battery that holds 5,000 mah. There are many other usb battery packs, however the others are typically much larger or more expensive. There are even smaller usb battery packs than the Pebble XT, however they hold much less power. The Duracell Instant Power for example holds 1150 mah, so it holds less than 1/4 of the power of the Veho Pebble, while being half its size.