Quoting TheOneKEA at http://www.linuxquestions.org/questions/linux-general-1/keeping-a-process-running-after-disconnect-150235/:
nohup is what you want - it's a wrapper that blocks the SIGHUP signal sent to all applications connected to a terminal when that terminal is closed by the shell.
Just ssh into the box and start the command using this syntax:
[user@remoteboxen user]$ nohup /path/to/command arguments &
The man page explains it better.
