I'm loving the Game of Thrones series, but not having read the books it has been a bit difficult keeping up with all the various families, houses and their entanglements. The Game of Thrones Wiki has been a great resource to clear up my questions, but I wish I'd found Magdalena Maslowska's Illustrated Guide to Houses and Character Relationships sooner — it would have cleared up a lot of my confusion. Here's just a detail, centered on the Lannisters:
(Hat tip: Francisco Palm.) You can explore the details in the full-size version (click to enlarge), but beware spoilers if you're not caught up to Season 3 as it's showing in the US.
On the other hand, you could just work with the (slightly NSFW) Game of Thrones Cheat Sheet below the jump. It's not terribly helpful, but it captured pretty well how I had to refer to most of the characters for the first season and a half or so!