Buy a bottle of water and reuse it! Their are cups next to the water dispenser, but be a good steward and refill the water bottle over and over again!
Bring a coffee mug to work. Sure there are styrofoam cups next to the pot, but bring your own cup. Sure you have to wash it everyday, but it sure beats all that white foam piling up in landfills.
Insulate, insultate, insulate! You can reduce your heating bill if you insulate your house. Check your windows, doors, anything that can be a cause of heat loss, even your electrical outlets. It's cheap to insulate and it will save you money and reduce your energy consumption!