DS (6 in Jan) or PSP not sure which yet. DD (10 in March) has a DS so that is what he says he wants but me and DH think he would be better with a PSP but do not know anybody who has one so he can trial it. Did the wii between the two of them last year..... a good investment for the whole family.
Easier to set up than hot wheels but does need care. Can take up a huge amount of room but depends on track permutation. When set up ds3 isn't allowed in the room. Does store nicely in it's box - no lumpy bits . We got a deal on the internet last year and since his most expensive Christmas present was £9 he kind of got the rest of his Christmas allocation for his birthday - think it was £99 but has lasting appeal.