+1 for Light Flow. It's totally cool and will make the flashing light meaningful.
You can select which apps will activate the light, what color it will be, how fast it will flash, times to have the light OFF (night?), how long it will keep flashing or turn off, and more. It's fantastic. I know by the light if I've gotten a text message, email, MMS, incoming call, missed call, voice mail, calendar notification and if there's an update from the Play Store. There are more apps than this that you can tap into the light notification ... and it's GREAT!