Here are a few suggestions:
- ride the last mile at a cool down pace, unzip your jacket, etc. and don't overdress; immediately remove as much clothing as possible when you arrive and put it in a stuff sack (REI sells them)
- leave as much at work as possible, including shoes, locks, battery chargers, winter coat, umbrella, spare bike stuff
- don't carry anything unless you actually need it (leave the heavy wallet and keys at home)
- eat before you ride
- shower when you get to work if available, rather than before riding