Useful
If Code
{{#if:x| p | q }} gives "p" {{#if: {{{4}}}|[[{{{4}}}]]|'''N/A'''}}
http://www.mediawiki.org/wiki/Help:Extension:ParserFunctions#.23if
If Equal
{{#ifeq: string 1 | string 2 | value if identical | value if different }}
If Exist
{{#ifexist: {{{{{1}}}/list|{{{2}}}}} Guests|[[{{{{{1}}}/list|{{{2}}}}} Guests|Guests]]<br>}}
Collapsible table
{| class="wikitable sortable collapsible" |- |}
Finding where pages are linked from
http://wiki.tvnihon.com/w/index.php?title=Special:WhatLinksHere/PAGENAMEHERE