Window Body Tag
( onLoad & onUnload )

This page has info on using JavaScript with events onLoad() & onUnload() from the <body> tag.  IE & NS work differently (as of IE5.5 & NS4.7).  In summary, Netscape will not call the onUnload() event when the browser is closed by clicking on the "X" button in the top right corner of the browser window.  Netscape will call the onUnload() event if the browser window is staying open but going to another URL.  IE will call the onUnload() event in all cases (Great job IE!!!!).