Ah, I’ve finally found a nice little CE-certified power supply for USB:
Extremely small (i.e. easy to ship), and very efficient. This thing will provide up to 1000 mA at a stable 5V level. Perfect for JeeLinks, JeeNode USB’s, and Arduino’s – or any other USB devices for that matter:
The power consumption when idle is a mere 0.20 watt, i.e. less than 1 mA of mains current. When plugging in a JeeLink, this increases to 0.32 watt, which is pretty phenomenal actually: the difference is 120 mW @ 5V = 24 mA, just about exactly what the JeeLink consumes with an ATmega running full-power and the RFM12B in receive mode.