I actually had to send some snail-mail recently and remembered the clever Google map envelope trick from Beste Miray Dogan that made the rounds awhile back. Turns out, a friendly bloke named Stephen has created a handy generator website that lets you input your return address and then automagically creates a printable cut-and-fold pattern.

More:

• AirMail: Felt / homemade Manila envelope laptop sleeve for MacBook Air
• The minimalistic no-cost iBook sleeve (it’s an envelope too)
• Letters without envelopes, cutting or glue
• Envelope and Letter Folding