The most promising battery currently available that I'm aware of for ebikes is the A123 20AH prismatic cell. It's very compact, holds a big charge, can be used at 30C which translates to 600A continuous, is nearly indestructibe, and is very inexpensive right now. I was eager to buy 12 or 14 for a 36V pack (with spares) for my Tidalforce bikes but then heard about a preassembled pack of 7S3P available for a similar price to the 14 separate cells... The 7S3P pack looks like this:
It looks as if it's all set up to go into an automobile or other vehicle since it has a strong plastic case surrounding the battery cells. Inside, it looks like this:
It looks as if the balance wires come right out to the outside and the 3P packs are very securely held in place with bolted down plates. I'm eager to find out more on these cells and it looks like lots of other endless-sphere.com folks are as well.