i'm buying my nephews monkey king toys since we don't have them in the states.  also a model of the china high speed train.  but be careful, toys here have a bad reputation (lead paint).  so i only buy from places i trust.

Chopsticks and tea sets, the kinds of gifts people back home smile and say thanks when they receive it, but then it gets put away and never seen or touched again.

This may not seem very traditional or Chinese, but I sometimes just get them those Starbuck city series "collectible" (riiiiight) coffee mugs (ie. Shanghai, Beijing, Hong Hong editions) if you are fortunate enough to live in a city which has it's own edition.

I'm going through the same dilemma. I bought a swag of Russian made stuff which is available in north east China - close to Russia I guess. I have some unique stuff like papercutting and a copy of qingmingshenghetu. Those little charms that you hang over your door or on a handbag or on a car mirror are a bit different as well. Finding that one little store that sells traditional stuff is the secret. Still looking. 6 weeks to go!

Organic Yunnan Coffee. It is something Chinese that is actually usable in the west.