Daniel is very astute. Not only is it difficult to get a pleasing background, but outdoor super wide angle (SWA) shots can end up with a lot of foreground and sky. Sometimes, that's just the point, as with ghosthex's very nice photo above. (It often helps to be above the subject and point the camera down.) Sometime, though, it can be a real pain.


Below is an example of "wide-open spaces." It's not very interesting, to say the least. (Unless otherwise noted, these were all taken with a Canon 30D & Sigma 10-20mm f/4-5.6 lens at 10mm, equivalent to 16mm for full-frame.)





It's pretty terrible. I took it just to see the result. It was the first time I'd been in a field that flat and expansive with that lens.


If you shoot buildings, you may get what some call the "parking lot" effect:





There's more sky and parking lot than building. You could crop the picture, of course, especially for a web page. (Sometimes, it's better to use a longer lens--e.g., 50mm--and take several shots and stitch them together. That has its own problems, however, including parallax.)


Here's another wide shot, but it's a lead-in to the major point I want to make.





Now, suppose that you got down (literally, in this case, on my belly) and, instead of showing a wide expanse, moved in close to an interesting subject, like:





That's the patch of Queen Anne's Lace, etc, in the middle of the previous photo. This could be sharper/more in focus, but, even with a short focal length lens, the depth of field isn't enough to get more of the weeds "in focus." I compromised between aperture (f/8) and shutter speed (1/160) @ ISO 100 because the wind was moving the weeds. (Some of the blur is probably from the motion.) I was hand-holding the camera, but had both elbows on the ground, forming a "bipod." I should have upped the ISO and gone for f/16 or so, though that gets close to (or beyond!) the "diffraction-limited aperture," where sharpness starts to degrade. Still, the extra DOF may have been worth it.


My point is to suggest that, instead of--or, better, in addition to--thinking of a SWA lens as being for wide panoramas, think of it as a way to get "up close and personal"--really close. I'm not talking about "macro" photos, where the image is "enlarged"--those use a much longer focal length lens. I'm talking about getting right on top of the subject, with the front of the lens within inches of the subject. The minimum focus distance of the Sigma 10-20mm lens is said to be 9.4". However, that's measured from the sensor plane, not the front of the lens. On my 30D, the sensor plane is shown by a mark between the mode dial and flash housing. The front of the Sigma 10-20mm lens is about 5.5" from the sensor plane, so the minimum focus distance would be about 4" from the front of the lens. That's close! (The minimum focus distance of two of my primes--Canon 24mm f/2.8 & 35mm f/2--are about the same, but they are much shorter lenses, so the subject would be further from the front of the lens. The only lens I have that has a shorter minimum focus distance is the Canon 100mm f/2.8 Macro, at 5.9", which is just about at the front of the lens.)


Being that close to an object gives a different and often interesting perspective than we are used to seeing. (Note that perspective has nothing to do with focal length. It depends only on the relative position of the camera to the subject. The advantage of a short focal length is a wide field of view, so you can put the subject into context.) Objects look rounder from close up than from a "normal" distance, for example, and the foreground tends to stand out more from the background. (Or, conversely, the background seems to recede.) Here are some examples.






The lens was only 5-6" from the nearer apple. The apples were only 6-9" apart.








Here, the apples are at nearly the same distance from the lens, but the image still has more feeling of depth than if it were taken with a longer lens. In fact, a bit later, I happened to take photos of the same two apples with a 100mm Macro lens. I found this one in which the apples are about the same relative size, though it's obviously from a different vantage point. Still, you can see the difference in the perspective. One way to do this would be to grab both photos (with my Mac, I click, hold, and drag the image to an open folder window--you can also use right-click, I think) and look at them side-by-side.





One last example of the "up close" technique.








Those are oats, seeded by spillage from the stable, birds, horses' manure, etc. The area I was shooting in is a wildlife preserve (Fern Ridge, in Eugene, OR) that adjoins the stable's property. We can go trail riding through part of the reserve, though much of it is off-limits to horses and much of it even to people on foot.


One time that I deliberately used the 10mm setting for wide panoramas was to shoot lightning at night. I couldn't be sure where (or when!) lightning would strike, so I set up my 30D on a sturdy tripod, set it at ISO 100, f/5.6 & 30 seconds exposure. When the shutter closed, I pushed the release again, so I got a series of shots, each 30 seconds long, separated by a few seconds. (I played with the ISO & aperture to ensure that the photo still looked like night and that the lightning didn't blow out so badly that it smeared.) The 10-20mm lens was set to 10mm and focussed at infinity. (After reviewing my photos, I probably could have used 20-30mm, instead, as the storm was more localized than I had guessed.) Here's one result--not very good, but it was an useful experimment.





I cropped the image to home in on the lightning strike. (No sharpening applied.)





Again, not very good, but I learn the most from my errors.