They don't have a dedicated key, I suppose, (but then again, you have to hit <shift> to get parens…) but smart quotes are <option>+{ and <option>+<shift>+{ on OS X, and configured to be <compose>, <, " and <compose>, >, " on my Linux machine.

Smart quote are a bit of a pain, but they do look nice. Really I prefer em dash, en dash, ellipses; I regret that OS doesn't have a keyboard entry for bullet. (Then, Linux doesn't either, other than entering in the code point directly with Ctrl+Shift+U or whatever it is.)