Formatting Keyboard Shortcuts for Comments
It's extra handy to be able to do stuff like CtrlL and CtrlB when editing posts, because Markdown markup can be tedious. Can you give us this goodness in comments as well?
This does seem very similar to the feature Tim Stone lists. Speaking of keyboard shortcuts in general vs one specifically, personally I think this to be a great idea.
I'm still rather new but I have already had time to wish I could hit control B for sure :)
Better formatting tends to improve readability too; some people go the opposite way with it.