@matoz - glad you found them interesting!
The GrooveAxe is pretty cool - it's a PICaxe drum machine by grandtippler, although I did the pcb layout.
The German Gaming mag 'Gee' is doing a story on the SIDStick - I'm looking forward to that. I also put the SIDcog core on El Jugador, a game console I did - giant bomb loved it and did a little video.
The NoiseAxe is tough - I like playing with it, but it's hard making pleasing sounds with it. grandtippler also designed that with a PICaxe 08m.
For SIDcog, I want to do a fun little mini-synth. Johannes' code is set up to do it easily, but the hardest part is the UI. It's tough trying to design a UI that will let the average user make pleasing music but still be inexpensive and flexible.