Many makes of cell phones now sell chargers that plug into your laptop’s USB port, charging the cell phone or PDA throughout the night with a slow charge that should do the trick by morning. That way you save one entire slot in the brown extension cord. :-)
I also carry one of those cheap battery-powered charges…takes a couple of AA’s, which I stock for my camera anyway. Won’t buy you much time, but will work in a pinch when you have no other options and you have to make a call.
Actually a lot of other electronic gadgets besides cell phones have available USB chargers. If I have a choice between two devices with the same functions, but one offers a USB charger, then that one gets my money. Then I can skip taking all those different chargers with me. I can plug anything into a USB port to charge. And, besides that you can get a AC powered adapter that plugs into a 110/220 wall slot and has a USB slot on the other end. That way, when power is available, I can give things a quicker charge than the slower trickle charge that they’ll get from my computer. One adapter to rule them all!
And, one poster mentioned a AA charger, that’s great when you can buy batteries, but it doesn’t give a lot of a charge. I have something similar that has a dedicated LiIon battery inside. That gives enough juice to fully charge my cell phone and PDA several times without ever touching another power source, great for long trips when no electricity will be available. The adapter has two USB ports, one inbound for charging the charger and an outbound for charging the cellphone, PDA, MP3, whatever. You can charge the charger then with a USB port on a computer, or with the USB/AC adapter, or just any USB charger for a cell phone, etc. It charges up fast, and charges your device fast. I got mine from Proporta.com, but there are lots of versions from other suppliers. It’s smaller than my PDA and lighter, but packs a big punch. Note that mine says that it is for an ipod, but it will charge anything that can charge by USB.
I might note that there is another similar device for charging laptops, but that’s pretty expensive and specialized.