/ Published in: C#
This is about the simplest way I've found. See [this](http://stackoverflow.com/questions/1092463/getting-the-mac-address-of-the-remote-host) and [this](http://stackoverflow.com/questions/1092379/want-to-get-mac-address-of-remote-pc/1092392#1092392) at StackOverflow for more info.
URL: http://www.codeproject.com/KB/IP/host_info_within_network.aspx