LizardSystems Remote Shutdown allows for the remote shutdown and restart of a single computer or a group of computers.

This tool will provide the means to manage power for groups of computers, or a single machine, on a local network from a central location. Remote Shutdown also provides some easily launched network tools like ping, pathping, tracert, telnet, nbtstat, and nslookup. You can also add tools that you use often via the manage tools feature.

Set up is easy and you do get 10 days to test it on the unregistered version but they do require you to complete a simple registration to continue to use it for free (non-commercial).

LizardSystems Remote Shutdown Features:

Allows system administrators to simplify remote shutdown, remote reboot for single computers or computer groups on their LAN.
Custom groups. Users can independently create their own computer groups and carry out power operations on these groups.
Perform power management operations on all machines at once. Tasks are carried out simultaneously on all computers selected by the user, significantly reducing the time taken to perform operations individually on all machines.
Works on domain and workgroups. The application can work with computers in a domain or workgroup.
Power management tasks recorded in a log. Users see operation progress for each computer and the status of operations performed.