Here's a WikiBookmarklet for the NewRecentChanges function; it prompts for the period, which may be null (default of 12 hours), or of the form 1.5 (i.e., 1.5 days) or 1.5h (i.e., 1.5 hours). Any input may have other parameters appended, such as ?del or ?min=20. You can specify the period as a fraction (e.g., either 3/4h or .75h specifies 45 minutes).

javascript:var dVal=prompt("Changes for how long?",""); if (null!=dVal) {dVal=dVal.replace("h","/24");var qP=dVal.indexOf("?");if (qP>0) {var dE=dVal.substring(0,qP);dVal="?days="+dVal.replace(dE,eval(dE));} else {if (qP<0 && dVal.length>0) {dVal="?days="+eval(dVal);}} location.href="http://c2.com/cgi/RecentChanges"+dVal;}