Spoiler Tags - These tags are useful for hiding a series of text, items, lists, etc; users have to click the "view" link to see the hidden text. Often useful for contests, reviews, etc.
[spoiler]This text is spoiled![/spoiler]
Theres an addon at UBBDev which allows you to change the spoiler warning and referance it in the tag as:
[spoiler:This is the warning]This text is spoiled[/spoiler]