I recommend carved Chinese signature "chops".

They make a wonderful souvenir gift as they are beautiful to look at and can be personalized with your name in Chinese. You can pick them up easily in Hong Kong. Many shops can carve your name in the bottom overnight or can mail them to you. (I've done it both ways).

They come in many sizes and shapes from small ones to something like a good sized paper-weight. Fun to get them in the sign of your birth year (year of the rat, snake, dragon etc.). Prices depend on size, intricacy of carving and type of stone.

I'm sure they are available in Shanghai (I was too busy touring to shop :( ) as well as Beijing.

Example of Chinese Chop
NY Times Article about chops

Don't forget to buy the red stamp ink!