The new 56-69 AFS ED VR 1.4 should be the perfect lens to cover the gap between your 18-55 and your 70-300, and at $350, it's a bargain.
Sorry, I just couldn't resist. I just posted a reply to your JPEG v. RAW post.
It sounds as though you are getting fairly deep into photography and Nikons, so you may want to slow down until you decide exactly how far you want to dive into this hobby. The reason that I say this is that you are buying DX lenses, and from the sound of your posts and your enthusiasm, you may eventually want to move up to a full frame camera. DX lenses do not work well on FX (Full Frame} bodies.
I would suggest that (1) you use what you have for now, (2) read up on the topic and (3) zoom with your feet for now.