I got a message from a datacenter recently. They were looking for a server. Apparently the location information was mis-recorded (or forgotten). They asked me whether I could make the computer beep so it could be located. The DOS bell is CTRL-G. Typing CTRL-G (ASCII 7) was easy in DOS days, but is a little challenging in Windows land. I solved this by dusting off the WordPerfect Editor (see post here). The resulting batch file beep.cmd loops the bell until you break or close the window.
You can also create a file from the command line with the bell:
copy con bell.bat @echo off echo ^G ^Z
They found the server pretty quickly.