I know you can spend up to $500 Cdn, but you don't NEED to spend it all. Just get what you want, whether you use up the money or not.
A cool, somewhat fancy watch
New speakers for your room (if yours aren't great)
If you're from Ontario and are over 19, ask for LCBO gift certificates. Nothing says X-mas like booze.
Some DVDs
Expensive sunglasses
New jacket that's way more expensive than you should be spending.
ski or snowboard equipment (not the entire set, obviously, but replace something in your set if you already have an older set of skis, or a snowboard)
A TV for your bedroom
A bar fridge for your bedroom.
A raincheck so that you can buy a more expensive gift next year.