To the OP: Unless you're going full-frame, I'd look at alternatives to the Nikkor 14-24 f/2.8, and the Tokina 12-24 f/4 at $499 is a really great option there, saving $1300 over the high-end Nikkor. And it's a solidly built lens with extremely good sharpness wide open, great performance. Or the 11-16 f/2.8 for another $100.
Also, with a D90 or higher body, the previous generation 300 f/4 AF ED lens is a super option, typically you can find one in excellent shape for $500-600, saving $900-1000 over the current version. And, it's built like a military tank with superb optics. I've used mine with a D300 and the focus tracking is excellent on moving objects, even though it's not AF-S. With the right Nikon body (built-in AF motor and screw drive option) you can really get some good glass, and save a bundle.
I also have an 80-200f/2.8 (two-ring version) which they still make, and it's an excellent piece of glass, with very fast AF (great gearing in the lens) even with an older D50 body. It almost feels like a built-in AF motor, and generally 'pops' into focus. This lens sells for $700-800 used depending on condition, and will probably maintain it's value if you ever decide to sell it. Keep in mind that the AF performance on the D90 will be better than the D5000. The now-discontinued D300, often available refurbished for $1200-1300 if you look around, has the same very high performance AF system that the D700 and D3 series cameras have, which is flat out amazing - the best in the business, at least right now. It has blown me away as I have come to understand all it's capabilities...
I swear by the 50mm f/1.8 - a great little lens, and full of great creative possibilities with a DX body. I'm not sure what the issue with 'stagnant' or 'flat' lines ArtandStructure is referring to, but I love the little lens. Yes, it's a bit long for a "normal" lens, but that mild telephoto perspective combined with the fast f/1.8 aperture makes it a different creative tool than the 35mm f/1.8, and it's cheaper. Screw drive, yes, but no built-in electronics to add to the complications of the lens. It's purely mechanical, which may be why I like a lot of the older designed Nikkor lenses. Also, look down the road and consider the 85mm f/1.8 for $400, or the 1.4 version for several hundred more. It's a great portrait lens also, and is fast. Once you go fast, it's hard to go back. It's not just the ability to shoot in lower light, but it's the ability to render backgrounds out of focus that open up the creative ideas.
PS: I just saw your post where you won the D90 on eBay. Congrats! A good choice... I'd suggest getting rid of the 18-105 kit lens, it's really not that hot - apply whatever money you get for it to take advantage of that built-in AF screw-drive motor to look at all the good stuff out there in used-glassland... or if you can swing it at all, look for a deal (around $1000) on a 17-55f/2.8 DX Nikkor, a much better piece of glass than any kit offering, or if you really need the zoom range I'd look into the 16-85 Nikkor.
Lots of choices...used or new stuff. Happy hunting!!