B╨Panel is a small cdev/init combination that lets you configure the system beep by adding a text message to the standard beep procedure. What you get is a window popping up at beep time with a one-line message, then either a sound or a user-defined pause before it disappears. You can turn on and off the window and the beep separately (no signal at all, beep only, message only, or both).
You can configure the font and size of the text, the window location and size and the message to be displayed. To avoid bombs, quite a few environment checks are performed before the window opens. The Gestalt routine is also called, which means that B╨Panel won't work with systems earlier than 6.0.5 (I think). If the window can't be opened (weird situations like a program beeping and quitting before initializiong the Mac environment), only the sound will be played - if it's enabled.
B╨Panel can also be used to turn off the beeps completely, which can be useful to speed up run-alone software like BBS management programs.