I fidget non-stop pretty much. Didn't really know this until my current gf pointed it out. Here's a selection of the stuff I do:

- crack knuckles
- pick nose
- adjust glasses
- finger drumming
- foot tapping
- pick ears
- kind of pull ear lobes
- bite finger nails
- scratch head
- rub chin
- sniff
- blow nose
- adjust sitting/lying down position
- play with toes

there's probably more that's all I can think of now.