If you've got a coffee habit like I do, using disposable cups from Starbucks or elsewhere means throwing away 365+ cups each year (plus java jackets and plastic lids).
While I've always been a supporter of the idea of using reusable commuter mugs, I didn't do it for the longest time because of a dumb reason...the lid. The lids of the mugs were hard to get on or off (I cut my fingers a few times), and I didn't like drinking out of them either. Finally, I fixed my problem. It was an easy fix. Don't use the lid.
Using a commuter mug instead of a disposable cup might not only reduce waste but also save you money. At Einstein's bagels, mugs are $1.99 (and you get a free coffee with it). A small coffee is $1.39. A mug refill is $.99. If you get a commuter mug there, it will pay for itself within 3 coffees. Not only that, but I calculated I am saving $146/year by reusing my mug.
Don't drink coffee? Here's a secret: you can also do this for other drinks like tea, soda, and even water. If the 100 members of this community used 1 less disposable cup apiece each day, that would be 365,000 less cups going in the trash per year. University students: you can also campaign to distribute commuter mugs free to students and have the cafeteria offer a discount on coffee and fountain drinks when students use their mugs (they did this a few years ago at Washington University).
If you know of another restaurant that gives a discount for reusing a commuter mug, post it below in the comments :)