Mobile, battery-powered WiFi, complete with crazy facial expression
I don't have a good bag for the setup yet, but I should now be able to have mobile WiFi for 8 hours at a time. This suddenly makes my old Netgear Skype phone useful, and I've been carrying it around with me for the first time ever.
**UPDATE, 9 Feb 2009**: My friend's Linksys router's AC adapter crapped out, so I plugged in the battery (they both want 5V). Very useful thing to have in one's bag!