What grains to keep on hand

I know this is a pretty open-ended question, but what grains should I keep on hand? I've got the base grains covered, I'm looking for info on crystals, specialty, etc.

I just recently got a mill and want to start building a stock of grains to have to brew on a whim. I like to do an ESB pretty regularly, as well as IPA, APA, and some wheat beers. I also like to do a stout or porter for wintertime. Some malty ambers thrown in the mix. I don't really have a favorite.

What do you all have in stock?

This topic has been covered numerous times. However, I would keep your basemalts, then any specialty malts you use the most in your beers. If you have some staples you keep on tap, keep those grains and hops. That way if your running low, you can brew. I don't keep anything on hand that I rarely use.