A while ago, I posted about new Mindsensors.com sensors: here and here.
Rob McGlade was one of the beta testers of the NXTHotShoe sensor, and used to create high speed images, as shown here. You can find more information and applications (such as a time lapse video) on his youtube profile
I have recently been working with the PFMate: a device, used to control up to four Power Function receivers (eight motors) from one NXT sensor port. I've used this sensor in a robot arm, as shown in this video.
Furthermore, Xander has made a movie of a line follower using the NXTLineleader. You can find it here.