That really depends on what he likes, but here's some ideas:
Gift Cards
A Wii.
100 or more is a good number.
That really depends on what their interests are.
A case of beer.
A ring or flowers. Mabye a gift card to a store.
an iPod
cell phone or money
A 6 year old would most likely like a stuffed animal.
A really cute Scarf and hat.
legos or transformers or a toy truck
Toys,iPod,basically anything electronic