Widgets are a really great tool in wikis.
I have just learnt that if you put this code in the "other html" in the Widget tab, the Wiki will greet you by name. Neat.
<script language="javascript" type="text/javascript">
//<![CDATA[
document.write('<font size="3" color=#000000>');
document.write("Hello ");
document.write('<font size="3" color=#dd0000>');
document.write((wikispaces_isUserLoggedIn?wikispaces_username:"visitor"));
document.write('<font size="2"font color=#000000>');
document.write("!! ");
//]]>
</script>