Fred suggested the Forever Stamp in 2003. The Post Office caught up in 2006.
Around June 2003, I wrote on my blog:
But a better idea is what I call the “letter rate” stamp — stamps that don’t have a dollar amount on them, but are good for mailing a letter — forever. Buy as many as you want (at today’s rate) — when the rates go up you don’t have to bother with penny stamps or worse, returned letters. Ditto for the $3 express mail envelopes — buy as many as you want — their stamp is good forever. The Post office would certainly make more money from people buying early. Probably makes too much sense though.
LA Times from this morning:
This Stamp Could Be Mailed ‘Forever’ — May 4, 2006
WASHINGTON — The Postal Service is planning a “forever” stamp for letters, good no matter how many times postal rates increase. That means patrons could say goodbye to annoying 2-cent or 3-cent stamps that have to be added every time rates go up.
Three years. Not bad.