Some time ago I ran across this article. While I don’t advocate using all of these very often, there might come a time when one of them proves very useful to force someone to take a second glance at a particular sentence. Then again, it might just fit so perfectly with the sentence that there is no question about it being just the right punctuation for the moment.
13-punctuation-marks-that-you-never-knew-existed
Let me know in comments if any of these really strikes you or if there is one of these that you might have actually found good use for.