Strikethrough, Underline, Overline, Small Caps, and Tiny Text
All of these effects are normally done with HTML codes. However, if you’re posting a comment into a site which doesn’t allow you to use HTML tags, then you may be able to simulate those effects with
combining diacritics (applying a line diacritic to each character in the first three examples), or using unicode characters to replace the letters (in the last two). When you do that, you get examples like the below which can be copied and pasted into unicode-compatible comment fields, and displayed by anyone whose browser supports these characters and diacritics:
Of course, that’s all just the beginning. There are a variety of other effects that can be accomplished by applying diacritics to characters (and
they are additive): R̊i̊n̊g̊s̊, c̸r̸o̸s̸s̸h̸a̸t̸c̸h̸i̸n̸g̸, r̾i̾s̾i̾n̾g̾ s̾t̾e̾a̾m̾, s͙t͙a͙r͙s͙, and even ͢Arrows! (Although the last can only be done to the first letter/character of the word/sequence.)