Livejournal's newest release gives us SPOILER TAGS!
According to them, "Though similar to an lj-cut, an lj-spoiler does not require a new page to load when clicked. Clicking the link will expand the hidden text inline. Plus, it works on both entries and comments."
Spoiler tags are pretty similar to the lj user and lj-cut tags: you simply type spoiler spoiler spoiler
Obviously large chunks of spoilery text like articles, pictures, etc will still have to go under traditional lj-cuts. This is just for small spoilers, like for things you aren't sure about. And remember, it can be used in comments, too! No more white-texting! Yay! (You can also use it for things that aren't really *spoilers* but that might be NSFW or sensitive, or take up a lot of space. And you can do it more than once!)
Feel free to practice in the comments and if you have any questions about spoilers or lj codes or what have you, please do ask. :)