You can fill altered paint cans with just about anything. Here are some ideas:

Anything you would put in a basket
Crayons/art supplies for a child
Toy cars or army men for child
Bath goodies
Cookies (I did this last year for about 15 people)
Use as an Easter basket for Easter eggs
My dd has one with her stickers in it
Beach Kit with towel, sunscreen and flip flops
Gift cards (use the quart or pint sized cans)
Candy--the clear cans work great for decorated Hershey bars
School Supplies
Trash can for tabletop
Storage for yarn balls.....