The software lies within System Tools, more precisely General.
From the developer:
NMS is a faceless application that forces system sleep at a set idle time or on Screen Saver activation. It can simply follow Energy Savers settings in an "install and forget" way or operate completely independently. For me this solves the recurring problem of an invariably corrupt power manager preventing automatic sleep and the frequent dead batteries that result. Simple as this solution is it has worked great for me. My laptop ALWAYS sleeps.
You may want to check out more Mac applications, such as VMeisoft Denendency Walker or Net Monitor Sidekick, which might be similar to NMS.