limited edition Nintendo DS (original). 3 months before UK release they were on the stars catalogue and I got one. Came with a demo for metroid: hunters and warioware. It may have come with Mario 64 too but I can't remember if I got that later. It came in a limited edition 'vip' box with a t-shirt with the DS logo and 'touch me' written on it. I think there were 3000 up for grabs from the catalogue.
I also have the legend of zelda collector's disc with Zelda, Zelda II, OoT, MM and a trial of Wind Waker (20 mins of the game) but I don't know how rare that is.