So here I am thinking to myself, there is a 6D out there, a 5D Mark III, etc etc. and now I have the 7D, what should I do. But I make piece with that and start hunting for a list of must have gear if you own a 7D and surprisingly, there just aren't things like that out there.
I have a family, I take pics of them. We go places, I take pictures when I go places. So from a stills perspective, The only thing I have right now is a 60D kit lens and a 7D body and a battery. Looking for a little 'christmas wish list' advice from some 7D owners.
I suspect there are not lists like you're looking for because people do different things with cameras. Anyway, given what you've said, here are a few thoughts:
1. Mount Smokey gave you the best advice with the EF-S 17-55 lens. It' got a good range. It's fast. It's got IS. And you'll get extremely hig IQ pictures.
2. As with any good camera, you'll need a second battery. Keep a spare charged so you'll never run out of juice when you want to be taking pictures.
3. Make sure you have good fast storage cards. Lots of excellent sales happening now. The 7D can flip along at a good FPS pace -- good for getting pics of moving kids.
4. The 7D has a flash so unless you're doing more than fill or serious lighting a flash wouldn't be high on my list.
5. If you're traveling around and doing some scenery you may want a good CP filter, once you've decided on what lens you'll be using for such things.
I think that's the basics. Next tier, I'd go first for one of the 70-200mm L lenses.