You seriously need to get ur wii off the carpet! Not only is the carpet acting like an insulator but all the carpet fibers are getting sucked up into the fan propeller.
A good idea for all u guys to do is to take ur mom or dad's sweeper (do just a little manual labor, it wont kill you) and vacuum all the vents on ur wii. this will get all the dust and particles that collect out of ur wii. Even if ur wii is not close to the ground, you get dust in there.
As for a cooling fan i was thinking about getting one but never really motivated myself to spend the money.
With ur wii on the carpet you also run the risk of static discharge on ur wii. This causes major electrical problems.Even thought it may be the perfect place for ur wii, I would SERIOUSLY MOVE IT!