Cars I watch out for:
- Prius
- big SUVs
- UPS delivery truck
- minivans
- "fun" cars on a nice saturday (mini coopers, etc)

Also, any car pulling out onto a somewhat busy road. They appear to be incapable of judging speed. Often they will see you about 10 car lengths back, sit and wait (you think they will wait til you pass), then when you are 10 ft away they gun it.