These are a few I know:
Spoiler Tags:
SMALL CAPS:
Make the entire text in capital letters, then set the size of what should be lowercase to 85. Remember to keep spaces and punctuation size 100, though.
Text in [sp.] tags will only be colored if the [color] tags are inside the tags.[hr][/hr][hr] tags:[/b]
It's just a horizontal page break. Don't put anything in them.[hr][/hr][quote="TurretBot"]Not really a trick, but here's how [anchor] and [anchorl] work.
[anchor.]words[/anchor] = where the anchor will send you to
[anchorl=words.]anchor[./anchorl] = link that sends you there
Though it doesn't have to be "words", it can be anything as long as it matches.[/quote][hr][/hr]
A really big thing is that you can, with the exception of those in locked threads, quote a post to see how the BBCode works.