http://www.safetmailer.com/

Apparently you can't get 'em because of the virus?

I have used them since the beginning of this year with no problem as long as the "penalty rate" for non-machineable postage (think it's 70c) is applied. At least, I don't know of anyone who had to pay postage due, I'm sure someone would have complained about that if it was charged. But I deposit such envelopes in a mail slot at the post office and run (OK, limp) outta there. If you had such an envelope to a clerk, it will be declared a Small Packet Containing Cardboard and you will have to pay $4 or so to mail it.

Still, the Safe-T-Mailer is a handy way to protect chips and tokens!