openInTab.user.js

// ==UserScript==
// @name			JavaScript Open In Tab Menu Command [TEST]
// @author			Erik Vold
// @namespace		openInTab
// @include			*
// @version		1.0
// @datecreated		2010-03-23
// @lastupdated		2010-03-23
// @description		This simple test userscript will create a menu command which will produce a javascript alert with the provided string or ask you for one.
// ==/UserScript==

executeFunc = function( str ){
	if( !str && unsafeWindow.ubiquityGMInput && unsafeWindow.ubiquityGMInput.length ){
		var str = unsafeWindow.ubiquityGMInput;

		// reset for next execution
		unsafeWindow.ubiquityGMInput = "";
	}
	else if ( !str ) {
		var str = prompt( "Input:" );
	}

	var win = GM_openInTab( str );
	alert(win.toString());
};

GM_registerMenuCommand( "open tab", executeFunc, "o", "control alt", "o" );