[theonlychuck]

they actually carry an item made to stick on your cap like that at my local wal-mart. it has 3 led's if i'm not mistaken, and has 2 clips on it and is slightly rounded so it hugs the bill of your hat.

these are similar, but sit ontop of your hat instead of under it, the one i seen sat under.

http://www.walmart.com/catalog/product.do?product_id=5839255

http://www.walmart.com/catalog/product.do?product_id=5839256