Check the brakes inside the rotor, check and lubricate your axle.
If you hear noises, just replace the damn thing. Buy it on ebay, install, check if it solve your problem, then if it is not, return it back to the seller!!!

This is my bad bearing:
http://www.youtube.com/watch?v=-6OvaQvAgAk

As you can see, wheel has a little play. But there is no way to find out on the front wheels unless you spin it with high speed.
Also, when you remove rotor try to rotate the hub with a hand, you'll feel that something is not quite right.

 

i replaced with the new one today and no more sound. I don't get why the new one has the same burnt color around the bearings body..lol
also i tried to tighten up the rear wheels and they were loose..that might have caused the sound too,

 

cool.. least it was a simple fix

 

Sorry to bring this thread back from the dead but I too get that noise from my car!! I will have the front bearings replaced and see what happens.

 

Don't get Timken.
after a month, i have silght clicking noise. They are under warranty for a year but still, taking them off sucks