Not sure if this is possible or not, but the routers functionality seems to hint at this.

It is able to detect interference from non wifi sources, eg turning on a microwave changes the Interference Level from Acceptable, to Severe

I have also seen tools such as the wi-spy which can provide a graphical readout of the noise

What I would like to know is, is this possible with a standard wifi card that detects noise, or can it be added to the router since it is clearly able to detect noise from on specific channels (eg if I set the router to channel 2, and set my other router to channel 2, then torrent with the other router, the inferference level willskyrocket for the wnr3500l v2. Furthermore, it detects noise from devices such as the microwave, (even when no wireless devices are connected to the router, so it is not like it is getting errors from dropped packets.