PRAM Battery Checker for Mac

From Polar Orbit Software:

The PRAM battery is a small battery on the computer's motherboard that allows the computer to remember certain important parameters when the power is turned off such as the current date and time. When the PRAM battery dies it can cause system crashes and strange behavior in your computer and needs to be replaced. This program gives you a simple way to determine when that time has occurred. This is a problem will occur to all Macintosh computers during their lifetimes.