If you want to style your text to look awesome in Facebook comments - choose Stripy. It makes your letters big and stylish, or very contrasting and turns your text 90°. But I warn you, it looks best in comments. Not in statuses, not in chat. Because stripy letters are enormously huge. And in fb comments font size is smaller than in every other part of Facebook, and if you multiply it by Stripy's 8 characters in width you'll get some awesomely readable text.
You can type English characters a-z, A-Z, digits 0-9, and punctuation signs ., !?:)(><"'-=. I thought they're all you might need.
Symbols that Stripy uses are: ▄█▓▒░─