Is it better to store chocolate in the fridge or at room temperature?
Chocolate should be stored in a cool, dry area whenever possible.  A cold basement or wine cellar is perfect.

Moist environments, including the refrigerator, can cause the chocolate to bloom.  This is when the cocoa butter separates and you start to see a white film at the top.  It's actually still safe to eat this way and won't even affect the flavour much, it just looks a little odd.

That said, even tempered chocolate (i.e. baking chocolate squares) will melt at hotter room temperatures, so if the air is humid or you're in a hot climate, you'll typically want to refrigerate.  Also, if you've just melted the chocolate to make a coating and haven't tempered it, then you must refrigerate it as it will melt even at colder room temperatures.

Otherwise, it's best not to refrigerate.  It will generally keep for a year or more at 55-60° F (about 13-15° C).