For any photographers?

I have a Nikon D3000 camera and was looking to buy a lens that would be good for landscapes. Anyone know of any lenses they think are good and would be recommended to use for landscapes that fit my camera?

The Sigma 10-20mm f4-f5.6 is an excellent wide angle lens for dramatic landscapes if you want wider than the 18mm your kit lens gives you. It has Sigma's in lens focus motor (HSM) so will autofocus on your D3000. There's a more expensive fixed aperture (f3.5) version, but not strictly necessary unless you are doing indoors shots.

Don't forget though, that most lenses can be used for most purposes - a telephoto lens can take good landscape images - in fact it's great for isolating elements in a landscape when you want to simplify & don't want too much in the image.

For example this was shot at 65mm;

I have the Sigma 10-20mm though (on a D300) - here are some shots I have taken with it;

There's also a Flickr group with this lens so you can see its results on different cameras;

Truth is, with experience your 18-55mm is pretty much all you'll need. It's nice to have something ultrawide, but really it's of very little use. I've been shooting landscapes for years, and do keep an ultrawide zoom, but I'm rarely shoot at 17mm (on FX sensor) and usually use the longer end of the lens most of the time, and that is actually covered by an 18-55mm lens. For landscape, it also doesn't matter that your 18-55mm isn't great wide open, you'll be stopped down to f8 or slower and working on a tripod anyway. The only thing is that if you are planning on travelling light, then a good prime may be useful to have. Unfortunately because of the simplicity of your camera (no AF motor, and no metering without a CPU), you do have to spend a fair bit on a manual focus only lens, something like the AF Nikkor 20mm f2.8 D or the Sigma 20mm f1.8 EX DG, both are AF lenses but don't have AF motors and need to be driven, but it's a sacrifice worth making if you need the lightness in a landscape lens.

What might sound counterintuitive, it is a good idea to have a telephoto lens in your arsenal. Something between 85mm and 135mm is my favourite (though here this was done at 400mm! ) I'd actually have a look at the Tamron 90mm f2.8 macro, it's a good length for picking out a certain bit of a scene, by framing it tightly and controlling the depth of field. Plus it's additionally versatile being a 1:1 macro lens, and also an accomplished portrait lens too.

There's no such thing as a lens that's good for landscapes. It depends on what sort of Landscapes you want to shoot. You have spent a good bit of money on an excellent camera that is part of the Nikon range of cameras and lenses. I'd suggest you consider sticking with the Nikon brand if you can afford it, buying second-hand lenses from reliable sources if you need to keep costs down. A good Nikon lens will give you years of service, will fit your and it's operating system, and will have a good second hand value should you decide you don't want it anymore. As for the the type of lens you need, there's an excellent lens "simulation" tool on the Nikon website that shows you what each lens length will do to a subject.http://imaging.nikon.com/lineup/lens/simulator/index.htm.
The factors to consider are Cost, Speed (Measured by the "F" number, the lower this number is, the more light the lens gathers and the more use the lens will be in lower light conditions) Compatibility with your camera, Quality - (read the reviews online, basically, how sharp is it?) Focal length (Gives you the angle of view, what sort of pictures do you want to take?), weight (you are going to have to carry this lens with you!) with Vibration Control or not? Front filter ring size (you may want to fit filters one day, if all your front filter rings are different sizes you will need lots of different filter solutions). If you consider and understand all the above factors, you will not go too far wrong when you choose your lens.