I see this usage a fair amount on some forums -- "Spoiler" is a button, and then you click and the spoiler unfolds.

I also know a forum which can use "spoiler text" (I believe forums.sjgames.com calls it "fnord" text?) which auto-maps the text color to be the background color (whether it's on the forum's posting background, or quoted-text background). You read by highlighting the words, and there are blank lines there. TVTropes also does this form.