While walking through the Flatiron area last month, I passed by this site. Starbucks was setting up tons of paper cups for a commercial. Ironically, the commercial was encouraging people to save trees by not using a paper cup.
Anyway, on April 15, Starbucks will give you a free brewed coffee when you bring in a reusable travel mug.
In other thirst-quenching news, Jamba Juice is offering a Buy One Get One Free deal with the coupon above (expires 4/25).