I stumbled across the Code2000 font while typing up some revision notes which required “outline brackets” (Unicode characters 27E6 and 27E7). None of the the fonts on my computer seemed to include the symbols I needed.
If you’re ever in a similar position, you can download the font from James Kass. It includes most Unicode characters, so chances are that if a symbol exists, you’ll find it. It’s a TrueType font, which means it should work on Windows, Mac OS X and Linux.
Code2000 is a shareware product, which means that if you like it, you should pay the registration fee (currently $5 which works out as around £2.90) – a bargain, methinks.