I've noticed on a lot of forums there are tags. They are exactly what they sound like. Some forums simply change the background and text colors to black, so that when you highlight it it shows the spoiler. I've never thought of this as needed on BYOND, because very little of the forum is related to non-BYOND stuff. But now days, with guilds being picked up, I'd hate to be checking the forums for the Heroes guild after missing the last episode and only to find a big fat spoiler embedded in a post.

Just a simple suggestion.I got the idea from the Facepunch Studios forum.
I'd second this. It is a handy feature to have for the guilds.
In response to Dice1989
You should have posted the Heroes spoiler right there in big, fat lettering. Y'know, seeing as how you had the first post.
While not as convenient, the code <font color=#CCCCCC> can make text appear transparent until it is highlighted.