How do you find 40k Tournaments?

As I continue to paint and play more and more, I have a question to the 40K community... How do you find out and register for local 40k tournaments? Tournament gaming is naturally the next step in my gaming career, yet I know so little about it. I know the local GW store host a game from time to time, however I know there has to be more out there... Outside of googling it and searching obscure forums, any central location that hosts all of this info? How do you find out about local (within 2 hours drive) 40k tournaments?