The cameras on most smart phones tend to be rather simple affairs so it's not surprising that savvy inventors have dreamed up numerous add-on attachments such as mini-microscopes and wide/telephoto adapters. They do tend to be rather elaborate and brand-specific, however, not to mention somewhat pricey. Not this one though - the Macro Cell Lens Band is a simple close-up photography solution that has two definite pluses - it works on any camera equipped phone and it's very inexpensive.
The Lens Band is decidedly low-tech, just a thick rubber band with a thin plastic lens smack in the middle of it, but judging by the sample shots, it produces surprisingly good quality images.
Installation is quick and simple, take the band out of your wallet or off your wrist, wrap it around the phone with the lens positioned correctly and you're away.
PhotoJojo sells the Macro Cell Lens Band for US$15.