You need to close the font tag so it's
<script type="text/javascript">
var memColor = new Array();
memColor[memColor.length] = ["Administrator","<font color='#FF0000'>","</font>"];
//Created by Agent Moose (revolutionx.smfforfree3.com)
if(location.href.match("topic,")){
for(f=0;f<memColor.length;f++){
$("div.smalltext").each(function(){
if(this.innerHTML.match(memColor[f][0] + "<br"){
$(this).prev().children().html(memColor[f][1] + $(this).prev().children().html() + memColor[f][2]);
};});};};
</script>
And yes, to do the crown do:
<script type="text/javascript">
var memColor = new Array();
memColor[memColor.length] = ["Administrator","<img src='crown.gif' /><font color='#FF0000'>","</font>"];
//Created by Agent Moose (revolutionx.smfforfree3.com)
if(location.href.match("topic,")){
for(f=0;f<memColor.length;f++){
$("div.smalltext").each(function(){
if(this.innerHTML.match(memColor[f][0] + "<br"){
$(this).prev().children().html(memColor[f][1] + $(this).prev().children().html() + memColor[f][2]);
};});};};
</script>