Something I found quite nice was a web series by Wil Wheaton: TableTop (http://tabletop.geekandsundry.com/) which basically consists of a round of people playing a board game, explaining the rules and generally having fun doing so. The nice part is that you can experience how the game is played and whether you might like it or not – much better than just with a verbal description or review on Amazon.

Of course, for cities that have such a thing, a dedicated board game shop where you can try out games is even better, but those seem to be rare, even in Germany.