In April 08, SingPost launched the first beaded stamp in the world to commemorate the opening of the Singapore Peranakan Museum. The beads are 'caviar beads' which are hand / manually pasted onto the stamps. Here's a picture of the 'collector's sheet' which is in the shape of a pouch with a $5 stamp.
Overall it is quite a unique set. There are two different designs for the four denominations (i.e. total 8 different stamps) - 26 cents, 32 cents, 65 cents and S$1.10. SingPost has also received an award from the Heritage Board at the same time when this set of stamps was publicly released.