Duracell's new PowerSource Mobile 100 could be the new best friend of anyone who tends to carry a lot of gadgets around. It can extend the runtime of just about any portable devic—and even provide up to two hours of additional juice for your laptop. If that wasn't enough, it also has one AC outlet and two USB charge ports so you can charge multiple devices simultaneously. I would completely fall in love with it if not for the $140 price tag. Unfortunately, convenience never comes cheap. [Product Page via Ubergizmo]
$140 for 4000mAh? underpowered and overpriced. Plus the product doesn't mention that it might not be compatible for your laptop.
I've seen 20000mAh units out there for $120. I've also seen battery units that look like laptop cooling pads that sit underneath the laptop. Just google "external laptop batteries" and you'll be able to find much better models available.