Would you like to get Free stickers from Google Gmail to place all over you stuff at the office or at home..? Then simply just send a self-addressed stamped envelope (along with a note if you’re so inclined) to:

Send me some Gmail stickers already
P.O. Box 391420
Mountain View, CA 94039-1420

Make sure to include enough postage to return a sticker pack via U.S. mail. It’s less than one ounce, so a standard $0.42 stamp will do if you’re in the United States; enclose an international reply coupon (IRC) if you’re outside of the U.S. And be sure to send your envelope in soon — one per person please.

Source: Official Gmail Blog