TNT has launched a new web game called Last Defense to promote Falling Skies. The game is a fairly standard tower defense type game so if you like those kinds of games, you may want to check it out.
I played it for a little bit but honestly didn't find it all that fun. There were also quite a few glitches, such as units ignoring enemies occasionally and the wave ending successfully even when there are enemies left on the screen. It's cool that they put up a web game to promote the show and it shows that TNT seems to definitely be behind the new series.