To display similar forums in other spots you can use this template code in any template area that's within the scope of a forum (this includes forum toplists):
<IF {CATNUMSIMILAR}>
<div id="similar">
{CATNUMSIMILAR} {LANG_DISPLAYLINKS_SIMILARCATS}:<br >
<!-- BEGIN SIMILAR CATEGORIES -->
{CATNAV[0 <,> 0 <,> 1]} <IF {SWITCH_COUNTS} and not {CATACTASLINKBOOL}>({CATNUMLINKSFORMAT})</IF><br >
<!-- END SIMILAR CATEGORIES -->
</div>
</IF>
<div id="similar">
{CATNUMSIMILAR} {LANG_DISPLAYLINKS_SIMILARCATS}:<br >
<!-- BEGIN SIMILAR CATEGORIES -->
{CATNAV[0 <,> 0 <,> 1]} <IF {SWITCH_COUNTS} and not {CATACTASLINKBOOL}>({CATNUMLINKSFORMAT})</IF><br >
<!-- END SIMILAR CATEGORIES -->
</div>
</IF>