Toolmonger points out that Wahl, makers of nearly indestructible* hair clippers, also has an entire line of cordless, rechargeable soldering irons under the "ISO-TIP" line. Each use NiCD batteries, but some take longer than others to recharge — from one hour to as many as four. Prices vary per model, from $50 to $100.
The ISO-TIP irons look like they haven't changed design in thirty years. In this case I consider that a good thing.
* My little Wahl Peanut, which I use on my beard, has been on the fritz lately. I took it apart last night and everything appeared to be in order — there's really not much to go wrong! — but it keeps blowing out the safety circuit in the bathroom socket. The powerful little motor may be giving up after a year or so of daily use.