You basically click the app to run and your mac wont sleep, you can shut the case but it stays running. Very useful if you wanted to plug your mac into an HDTV and close the mac but still use a mac keyboard / mouse or iPhone to do things. This might be something worth looking at for you.
Mac App Store - Caffeine is in there but also look at: SmartSleep & Lullaby
You basically click the app to run and your mac wont sleep, you can shut the case but it stays running. Very useful if you wanted to plug your mac into an HDTV and close the mac but still use a mac keyboard / mouse or iPhone to do things. This might be something worth looking at for you.
Mac App Store - Caffeine is in there but also look at: SmartSleep & Lullaby
Several NAS units also have this functionality built in. For example with Synology units you can set a download going through the web interface or with a Mac-based utility, and the download will continue on the NAS independently of your Mac.