Check this out! It's a Lightbulb phone charm for any handsets, and damn it looks cool!
As you may guess, it starts flashing whenever you receive a phone call or SMS.
The Lightbulb is available in blue and yellow colors, is pretty small (3×1.6×1.6 cm) and uses three SR60 batteries (included).
The price is 5.95 GBP (about $12).