I have a D7000 too. Definitely a great camera for the price. Video-wise, it is kind of lacking though. Don't get me wrong, the quality is pretty good, but if you ever want to slow it down or anything like that (which is commonly used especially in skiing) it will be pretty choppy because of the low frame rate.
Just like you though I upgraded from a D3100. I bought the D3100 when it first came out and had it for awhile, then upgraded to my D7000. I hardly do any video though, so I didn't see the need to wait awhile for better video quality. Plus I was shooting a lot of low-light situations so I really wanted better ISO performance, and at the time I could afford a D7000 so that little step up is what I did.
Personally I'm going to say (just like everyone else said), get good glass first. Before I upgraded I bought a 50mm 1.8 and a 70-200 2.8 on top of my kit lens, which I found for awhile with those lenses, I had a pretty good range for what I was doing. Then I upgraded and was all set for a little, then bought more lenses haha.
Another reason I say to wait, is that in Nikon's new D4, they have 1080p at 30fps and 720p at 60fps (pretty sure). That's what the canons have been shooting at for awhile now, but at least we're finally catching up. Hopefully they'll move that good quality down to lower level bodies, so that's why you should wait and pick up the predecessor to the D7000 or better, the D400. If my money situation is alright when they release the D400, I might pick one up aswell and keep my D7000 as a back-up, hopefully. haha.
Good luck with your search for more photography stuff. It really is an addiction!
If you have any other questions feel free to PM me if you would like!