JUST DISCOVERED something. The Galaxy Nexus takes advantage of a "new" USB spec for charging. If the two middle USB pins (D+ and D-) are shorted together, it will charge at full power (1A or w/e). This is indicated in the Settings|Battery screen where it will say "Charging (AC)". When you plug into a USB port (or a charger that does not short those pins!) it will say "Charging (USB)" and will only charge at some minimal current level - 500mA, perhaps less. I noticed this when I was driving and using my Galaxy Nexus as the navigation, and even though it says 'Charging', the battery percentage was dropping.
I'm in the process of modifying one of my car charging adapters to short those pins together as a test, once I can find the missing spring that flew out when I opened it up.
EDIT: I put it together with one of the springs still missing. Charger works great and reports "Charging (AC)"!
