If you travel as much as I do, or find yourself commuting for long periods of time, hang on to your Contigo Travel Mug! As long as you don't forget yours in the plane, you'll be happy with the Contigo 20oz Travel Mug a.k.a. Best Coffee Tumbler EVER. It's a pure winner. It's 100% leak proof and the kicker stats are that the vacuum insulated double wall stainless steel keeps beverages hot for 6 hours and cold for 18 hours! It kept my coffee scalding hot for so long that I had to keep the lid open for over 30 minutes just so I could sip the darn thing! I highly recommend the 20oz version as it can hold a full can of soda with ice or a vent coffee. If you're wondering how it tests for cold beverages, I've tested it through and through and was able to reuse the ice for multiple can refills of Mug Root Beer for a couple of hours as it seemed to never melt.
Ideally, it's a tremendous coffee cup or coffee tumbler. Just hit up your local drip and filler up! In case you're wondering, I'm referring to Bird Rock Coffee Roasters!
Update: In 2013, I went through two Contigo Coffee Tumblers and one Zojirushi. I left them all in airplanes and have only gotten one back to yet leave it in another aircraft. I just bought another one today, February 1, 2014 and chose to go with Contigo as I wanted to actually be able to drink out of the tumbler within the first hour. The Zojirushi on the other hand, keeps your beverage scalding hot for over 2 hours so it's best for transporting and only enjoying a poured cup of coffee only in my opinion.