You're pretty much screwed. There are some devices out there that will charge off of a 9 volt battery, but they're not readily available (you'd have to order online), and also the reviews say they're crap.
Unless you're staying at a hotel. Then you can get something that plugs into the wall that you can plug any USB cable into. Those ARE readily available.
I found a hair dryer outside the showers at 9pm at night at the last Ride to Conquer Cancer. It was plugged in at the sinks. For yucks I tried it. It worked. I dried my hair outside... kinda strange experience (I was the very last person to have a shower that night so it was super nice to be able to get the hair dry). So... there is power there at the sinks (assuming the same setup is in use), but you'd have to stay with it as it charges, and you need to have an adaptor that runs off of normal plugs.
Most of the people that I knew with stuff to charge (i.e. GPS units for their bikes and cellphones) sent them away with teammates that were staying in a hotel.
Carolyn
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Weekend to End Women's Cancers - Crew Member - Camp Concierge 2009 and Caboose 2010 Ride to Conquer Cancer - Rider - 2008, 2009, 2010 and registered for 2011