Chocolate Shot Glasses
In order to get the chocolate to harden correctly, still look shiny, and have that nice snap when it is broken, you need to temper your chocolate. There are many methods for doing this, but the seeding method on this site is most people's preference:

http://www.cookingforengineers.com/article/155/Tempering-Chocolate

After that you tempered chocolate, follow this process:


Ensure molds are 100% dry
Fill molds completely with melted chocolate.
Tap the molds on the table or tap them with a spoon for a few seconds to get rid of the air bubbles.
Invert the molds over your bowl of chocolate and let them drain out, leaving a chocolate coating in the mold.
Place the molds face down over a sheet of parchment paper (or something like that) to let them drain out a little more.
Put them right side up again and let them dry for 20-30 minutes.
(optional) place the molds in the fridge for 10 minutes (will make demolding eaiser)
Invert the molds over a sheet of parchment paper. If necessary, tap gently or carefully twist the mold to get the pieces to release.


EDIT: First, if you are going with this technique, use real chocolate (the only fat should be cocoa butter). Second, if you can, use a high cocoa butter chocolate.