USPS Global Priority flat-rate envelope
Here’s a shipping option for international shipments that you may not know: UPDATE As of 14 May 2007, the small Global Priority envelope is no more. The large Global Priority cardboard envelope (to hold a 9×12 envelope) is $9.00 to Canada and Mexico, $11.00 to other countries. Use the small custom form, and you write the address directly on the cardboard envelope (i.e., there’s no separate form for that with a blister pak).
You can mail up to 4 lbs in the Global Priority envelope.
Also, there’s a flat-rate Global Priority (I think they now call it International Priority) box: $37 to Europe. It takes the larger customs form, and you get insurance coverage free, the amount based on the weight of the box.