This is probably the second most important piece of gear next to a good belt/holster combo. ;)
Anyway, I'm looking for a tumbler (i.e. mug w/o handle) to hold and keep my morning coffee warm during my commute. Right now I'm using a freebie that I got a couple of years ago from LAPG but it's not insulated and doesn't keep stuff hot for very long. It's sippy hole is also just covered by a piece of plastic that slides over it, so if you jostle it around enough coffee will fill up the outside of the lid.
I've looked at a couple of different Thermos models which might do the trick but thought I'd ask here to see what the rest of you carry.