Well, it was bound to happen. As you can imagine, there are tons of games out there. Some are commercial packages, and others are free for the download (or compile). Still more are in various stages of development and playability.
To satisfy your hunger for Linux games, you might take a little time browsing in the games section on either SourceForge (www.sourceforge.net) or FreshMeat (www.freshmeat.net). You'll find plenty there.
One of my favorite sites for games is the Linux Game Tome at happypenguin.org. Although not a download site, the Linux Game Tome organizes, reviews, and lets users rate games. It's organized and searchable, and it should be on your list when it comes to adding some new diversions to your system. If you are looking specifically to find games for the younger kids, check out Linux for Kids at http://www.linuxforkids.com.