Depends on what I'm cooking as to what I use as a thickner.
I have used:
crushed tortilla chips (chili's and really thick hearty stuff)
tater flakes ( I use these mainly when I make a boo boo)
flour / water (when I don't care about the cloudiness)
cornstarch / water (when I want thickened without cloudiness)
roux (when I want some color/flavor added to my dish/gravies)
probably a few others I can't think of.