I think the only place where I'd see a benefit with rechargeable batteries is at work, in my mediocre "noise-cancelling" headphones. The only other battery-operated gadgets I can think of are:
- Remote controls (self-discharge kills it)
- LED or MAG lights (used so infrequently that self-discharge is a problem here too)
- Digicam (uses its own special battery pack)
- Cordless phones and cell (use their own batteries/chargers)
- Various tools like laser levels and stud finders, again used infrequently
I think that's it. What else takes batteries? The only thing I can think of that really rips through batteries is a portable audio player, and since I don't take the bus, I don't need one of those.
Oh and josh, it's actually not like putting a moped motor in a pickup, it's more like filling the gas tank 1/3 of the way. It'll run perfectly fine, you'll just have to refill it sooner.