What is the best method for chopping up a block of chocolate?

The main thing is to make sure the chocolate is cool so it doesn't start melting right away. I use a large chefs knife so I can chop a lot at once. And you can use a pastry scraper to pick up the chopped chocolate and get it into a bowl. It still makes a bit of a mess but these tips should help contain the mess!

I just chop with a serrated knife, but you could put the chocolate in a ziplock bag and smash with a rolling pin, frying pan, or some such implement.