I live in Olathe, and the one people are mentioning is
www.brewcat.com. Sure, it is nice to have a LHBS so close, but I can't say I'm overly impressed with the place. They charge 20 cents a pound to grind the grain. I know this isn't much, but it seems like everyone else's LHBS does it for free. The lady that works there most of the time knows absolutely nothing about brewing beer, and I mean zero. I was hoping they would do a "brew day", that I read other LHBS stores doing, or would have similar events, but they don't. Charlie, the owner, seems like a pretty nice guy, and I would guess he's the one that makes all their extract kit recipes. I've only seen him in there once, maybe twice.
The other LHBS in the area is
www.bacchus-barleycorn.com, but I've never visited their place, so I can't comment much about it.
There is a kc brew club:
http://www.kcbiermeisters.org/. I really want to join up, but none of their dates have worked out for me. There is also another club in nearby Lawrence,
http://lawrencebrewers.org/main/. I've heard they do a lot of group buys, to get good deals on grains and such.
That's all I know about the area. I'm pretty new to brewing as well, so take what I said with a grain of salt (and a homebrew).