This has been around for a while, but I thought it deserved a mention. SolarSafe UV Monitor Wristband is a simple way of monitoring how much sun you have been exposed to. You simply place the band on your wrist, apply the same sunscreen that you are wearing onto the SolarSafe wristband and then enjoy the sun. The wrist band has three color changes depending on the amount of exposure.
Check the product out at Solarsafe