SKypad

I have personally had no problem with the plugs, and their sizes are the same size than any conventional outlet.

There there's the charger skypad 2 USB female plugs, one 500mA and another 1000mA.
No ground connection is useful for this kind of product, contrary to what can be said about the other comment.

A cap is provided for protected the cigar lighter.

Update: In hindsight this just seems essential accessory.