I think I've made it to the point where about 95 percent of my battery use is rechargeable batteries. The main exception is the damn smoke alarms in my house as they only seem to work with throwaway alkalines, even though they're hotwired and the battery is just a back-up.
There's always one big inconvenience though: most rechargeable batteries lose juice over time, so if you charge them up and leave them in a drawer, they'll be half dead when it's time to use them. Most lose somewhere around two percent of their capacity a day. So you have to charge them up close to the time you're going to use them.
The exception to this are so-called hybrid batteries, which come ready to use out of the package and are not so prone to energy evaporation. The ones that came with this Duracell Mobile Charger worked fine right after I wrestled wrestled them loose from the (non-recyclable) clamshell packaging and the company claims that they only lose two percent of their power per month instead of per day.
Then there's the charger. It isn't nearly as compact as the Energizer travel charger I reviewed earlier, but on the plus side it has a USB port. This makes it qualify as a good double-duty charger: you can charge up the batteries by plugging it in or charge up your MP3 player by plugging it into the charger. So you can recharge your tunes without powering up a laptop. Power flows out from the batteries too though, so in a pinch you could pop in charged batteries and send that power to your USB device. Also, this unit has four individual status lights, so you can see when each battery is fully charged.
The Duracell Mobile Charger goes for anywhere from $17 to $29 depending on whether you are buying one stocked with two or four batteries and whether it comes with a car adapter.
Get the car adapter version with 4 batteries for $21 at Amazon
Get one with two batteries only at Amazon