Hi

I have a son and a daughter, so for a boy, I'd suggest a scientific experiement toy, or something to make himself, like the kits you can get to create radio's, electrical circuits, alarm clocks or cars etc.
There are some great construction things out there, like lego playsets, meccano, magnetix or k'nex which is good.
My daughter is 4, and loves playing with dolls (lil bratz/barbie, disney princess). She likes building toys too, dress up, as well as Dora, Playdoh play sets, hand puppets and all pretend toys, like kitchen & cleaning sets, post offices, shop etc...

Craft items always go down well, and a child can never have enough crayons/felt tips (as they disappear into the strangest places in the home!)

Hope this gives you some ideas.
I've done most of my xmas shopping now. Spent the last 2 days wrapping them!

Take care

AmberUK