These two bits of software allow you to use your Nintendo DS touchscreen to control other software such as music making software, remotely over wifi.
With KnobsAndSlidersDS you can dynamically create widgets on the DS by sending it messages from your PC or laptop. You can interact with the widgets using the NDS touch screen, which will send messages back over the network.
With FUDIKaosDS you can use your NDS as a Kaospad style input which sends all touch-pad events and button event messages over the wifi to your music program.
The main use-case for this software is controlling Pure Data patches from the NDS touchscreen in order to make music. It's intended as a replacement for complicated MIDI controller hardware, or an expensive Kaospoad in situations where more portability is required, such as when travelling. It communicates on the local wifi network using the FUDI protocol supported by Pure Data. Apparently you can use it with Max/MSP too, and there is an included .pat file to do this which some people have used successfully.
This is a video that someone posted to Youtube featuring FUDIKaosDS (one of the two programs on this site) in action.