If you use a MacBook and are out on the road a lot, chances are the battery doesn't last quite as long as you'd like. One solution is a commercially available battery pack, but they're not cheap. So how about making your own for around £40?
Over at the Verge, there's a post that explains how to hack together CCTV batteries and a third-party car charger to make a cheap external power packt that can provide up to nine hours of juice. It's a pretty straightforward project—if you know which end of a soldering iron to hold, you should be OK—which could save you a few hundred quid. What's not to love? [The Verge]