Some things I use:

Sour candy
Strong mints
Rub ice cube on forearm
massage lotion into feet
Counting the number of items in a particular color in the room
Saying the alphabet backward
4 square breathing: breathe in for a count of 4, hold for a count of four, breathe out for a count of 4, hold for a count of 4
Concentrate on feeling the chair that I am sitting on, the floor under my feet, the temperature of the air