I made a bunch of chinese ribbons to wave around during the ceremony. Our guests will sign those ribbons when they come to the reception.

Some ideas I liked before ...
1) Photobooth or polaroid guestbook?
2) Mini guestbook pages on the table in a nice folder?
3) Traditional Chinese silk guestbook?
4) Sign a photo or quilt or something?
5)I really love this guestbook with hanging messages on colored glass.
6) Fillable round christmas ornaments that people can fill with notes, a picture, and possibly a silk or origami flower, then hang it on something. http://www.bjcraftsupplies.com/holiday/fillable-ornaments01.asp