a few favorites of mine:
color(s): red, black, blue, white, pink(depending on the shade)
ice cream: chocolate
animal: undecided among these: cats, dogs, horses, dolphins, wolves, eagles, swans, doves.
fictional/mythological: unicorns, pegasi, dragons, phoenixes.
car: don't have one
day of the week: any day I have off from work
season: spring(after a bit of thought)
holiday: Christmas
candy: pocky, among a few others.