A 6 year old would most likely like a stuffed animal.
A ring or flowers. Mabye a gift card to a store.
an iPod
Gift Cards
If he's your friend then he any gift would be a great gift so yes^^
You can buy fashionable and lovely clothing as a Christmas gift for a 20 year old girl at the Durant Square Mall in Oakland, CA.shopping online ,I think the brands good : oasap.com,forvere 21,H&M and so on,cheap and good clothes
Buy her clothes or jewelry. I am 11 but i still love that. If she is more tomboy get her video-games and stuff.
That really depends on what their interests are.
A case of beer.
Anything
A really cute Scarf and hat.
legos or transformers or a toy truck
Toys,iPod,basically anything electronic