I always see the battery life of the Kindle debated as a problem on mobileread. The
Tekkeon TekCharge MP 1550 ($25) combined with the USB power adapter from this
thread ($5) should give anybody almost unlimited battery options.
The two advantages I see to this solution is that AA batteries are available everywhere so you are never far from power. I personally have mine loaded with rechargeable Eneloop batteries which have very low self discharge rates. The other advantage is as mentioned in the thread above that you can keep on reading because the Kindle won't go into drive mode.
Whispernet to your hearts content mobile warriors.