***EDIT*** This kit is not ideal for an iPhone or iPod Touch in its stock form. It requires more than 2 AA's. It will work well for iPod Video and lower, however. See
this post for details.
So I ordered a kit from these guys tonight:
http://ladyada.net/make/mintyboost/
I'm very much looking forward to putting together a circuit again... albeit a very simple one.
The kit is only $20 (plus the cost of the altoids gum tin). They say it doubles the lifespan of an iPod video, so it should give me at least several hours of extra use per 2xAA. I have a ton of rechargeable AA's lying around, so I should be set for camping.
Of course I'll post pics of the process when I get it. Unless I seriously mess it up in which case... um... nevermind