http://www.icyphoenix.com/viewtopic.php?f=28&t=3701&p=25823#p25823
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moreteavicar
Mon 10 Mar, 2008 21:28

Re: Track Visitors To Your Website Using Google Maps
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Something else that might interest you. Heres some javascript to modify the google map to suit the browser window size.

Look for:
[code linenumbers=false]// *** Create the map instance ***
		var map = new GMap(document.getElementById("map"));[/code]

Replace with:

[code linenumbers=false]
var winW = 460, winH = 320;

  if( typeof( window.innerWidth ) == 'number' ) {
    //Netscape or Non-IE
    winW = window.innerWidth-16;
    winH = window.innerHeight-16;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    winW = document.documentElement.clientWidth-20;
    winH = document.documentElement.clientHeight-20;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    winW = document.body.clientWidth-20;
    winH = document.body.clientHeight-20;
  }

		// *** Create the map instance ***
		var map = new GMap(document.getElementById("map"),
                { size: new GSize(winW, winH) } );[/code]
*Edit* And if you display it in an IP page, with left sidebar / menubar, also subtract the left sidebar width. 
E.g. If sidebar width =180, then in the above javascript lines,  replace -16 with -196 and -20 with -200. If you want fixed width, just remove the if else lines and keep: var winW = 460, winH = 320; (change values to suit).