I'm going to buy this one-
MAX E6 Digital Lipo Charger
It's not as cheap as the one from DealExtreme, but they only deal with PayPal and I don't like to share my bank account info with folks on the internet, so PayPal is out for me.

I also like how the Max E6 comes with a bunch of wires, temp sensor, and software.
I found a 12V 2.5A power supply in the garage that will get me started.

Another option and one that looks very enticing is this
Mega Power Infinity-960SR w/ Balancer 12S
Also a copy of a high-end charger, but able to balance 12 cells! Perfect for the roomba batteries, but $200 and I'd probably have to get an upgraded power supply.
If things go well enough with the Max E6 and I feel the need down the line for the fancy-shmancy stuff then I'll spend more money for the better equipment.

One thing that has me confused is that each of these 'cell balancing' chargers only talk about being able to balance Lithium-style batteries. They don't say that they can *only* balance lithium batteries, they *only* say that they can balance lithium batteries. Subtle.
It's my impression that lithiums are very sensitive to being unbalanced during charge or discharge and other chemistries not so much (certainly without the danger).
So- I'm assuming that the ability to balance lithium cells should extend to being able to balance other cells, too, but the documentation doesn't say this explicitly.

I'll keep you guys posted how this system works out with my battery projects.