Screen is a nice little nix-utility that allows you to leave a command running on a remote server even if you have disconnected.
The utility has a site at http://www.gnu.org/software/screen/.
Use is easy. Start screen with screen. You can exit an existing screen by tapping CTRL-A, d. Re-attaching to a screen is done with screen -r id. You can retrieve a list of ids by tapping screen -ls.