MagiWOL is a freeware that lets you wake up or start your computer over LAN. MagiWOL uses Wake On LAN feature, that needs to be turned on in the computers that you want to wake up over LAN.
MagiWOL is quite simple to use. You just provide a name, and MAC address for the computer on the LAN that you want to wake up. MagiWOL also supports SecureON security password. So, if the computer over LAN have a SecureON password associated with it, you can provide that password in MagiWOL, and then wake up computer over LAN.
MagiWOL is useful for enterprise setup where a network administrator wants to wake up multiple computers. It requires .Net framework to be installed. It works on Linux also by using Mono (.net equivalent for Linux).