What should be the next camera I buy?

I'm a amateur photography slowly building up to being a pro. I currently use a Nikon d70. I'd like to remain Nikon. I just want something better than the one I have, but nothing really, really expensive. Eventually, I can get something Really nice, but for now I'm still in my learning phase, I guess you could say. Also, lens suggestions.
I'm also going to be looking into upgrading my editing software. Right now I'm using a Correl program, but most probably will go to Photoshop. Any suggestions? Remember that I only want something basic for now, I can buy something really nice once I have more profit coming in.

At the moment if you're still learning, just focus on the basics and build your lens library. Good glass is better than a new camera body. Suggestions for where to begin are fisheye, macro. Then build from there according to what type of photography field you are following.
In terms of software, you may want to look at Adobe Photoshop, but my personal favourite is Adobe Lightroom. It is dedicated to producing high-quality images, and is easy to use.

Just some general advice save for a really good camera, inching up to one wastes your money you will never have enough for the really good one because you keep spending it on the sorta good ones. I did this years back and found I was cheating myself. Learn how to use the one you got and keep saving till you can get an awesome camera.

You are far better off upgrading to good quality lenses than upgrading the body. What do you shoot with now?

If you are doing portraiture, you should have these (or very similar) lenses in your 'stable';
- 50mm f1.8
- 85mm f1.8
- 24-70mm f2.8
- 70-200mm f2.8

A faster version of the range covered by the kit lens (17-50mm f2.8) might also be handy.

Also, you want to think about investing in some off camera lighting if you are doing location or studio portraiture. A couple of speedlights, stands & modifiers as a minimum. Manual flashes will be cheaper (& more consistent) than TTL/Auto flashes.

You haven't said who your clientele are, but if you are planning on doing weddings, you would also need (in addition to the lenses/lighting above) a SECOND DSLR body as a backup. You can't do paid wedding work with a single DSLR.

As for software, Photoshop CS6 would be great, but if this is out of budget, then Photoshop Elements would be fine.