You have probably already played with photographing panoramas "the hard way", one frame at a time and then stiching them. There are other ways. One of them are photographing a sphere and using software to unwrap the image into a regtangular panorama image, which can be used for a interactive panorama.
NOTE - this is a older article written in reference to using my Olympus E10 camera, however this information applied equally to using any modern DSLR camera for the same process.
How it works
The technique is simple, take a crome sphere and place it anywhere then photograph it as close as possible filling the image with the sphere as much as possible (fig 1). It does not take much imagination to realize that this particular image now reflects everything around it, Figure 2 shows. Crafty software and Math people like Helmut Dersch have created great software which will unwrap this image and create a panorama, based on the understanding of the shape of a sphere. Problem with this technique is that the center of the sphere shows the stuff around the camera and have lots of details for the "floor" however the edges compressed the upper half of the image into a very narrow band around the edge of the sphere. The result is that there are very little information for the top part of the panorama. The ideal process would be to create a egg shaped sphere (well it would naturally no longer be a egg) because it have more "side" area it will also give more details for the top part of the panorama. The tricky part is to calculate how to unwrap this shape since it is no longer a straight geometrical shape and the cameras position suddenly becomes critical to the result.
There is a number of reflector manufactors on the market, my favorite is the EyeSee360 mirror, which can be purchased from Kaidan. Another one is the VRinteractive , concave mirror reflector, this is a fun little reflector to start with, because it is reather inexpensive, but you will soon grow tired of its flaws. such as it see more ground than sky, causing the image to be distorted, still it is a fun learning tool.. There are several other brands of reflectors on the market, I prefer the EyeSee360 eflector because it allows me to mount it on my Olympus E-20.
All of these reflectors come with one or another software, some of them are based on a "per click" base, meaning that you pay a amount to output a final panorama image. This can quickly become expensive. I have found 3D-Vista to be a outstanding alternative to the original softwares, becuase it charges no per-click charge. AND if offer a GREAT preview feature, permitting you to see if the camera were not perfectly level when photographing, and to CORRECT this while seeing the result live. This feature along is well worth the money for the 3D-Vista stitcher.
Using the reflector
The reflector comes with a screw in filter for small digital cameras, but will not fit on the E-10 out of the box, so you need to create a mount for it first.
From your local photostore purchase a Cokin "P" Series filter holder with a 62mm adaptor ring and a 62mm UV filter. When you come home drill a xx mm hole in the filter with a eletric drill, do not apply a lot of pressure as it may splinter the filter. Then unscrew the reflector from its original mounting filter and attach it to your UV filter.
Now mount your camera lens up on your tripod and carefully slide the VRi reflector in place over it, use the zoom to get as close as possible, the viewfinder shows slightly less than what the chip actually captures, so you want to zoom in close enough to touch both sides of the reflector with the edge of the viewfinder. Finally focus the camera on the reflected image and start shooting. I suggest using the self timer so you can get out of the way when the camera photographs since it sees everything. Also put a two=way bubble level in your hotshooe and make sure the camera are perfectly level when you capture the images, as this is critical for the panorama, otherwise it will look like the ground are uneven when you look at the final result.
PTgui - Probably the very best stitcher on the market. Highly Recomended
3D Vista Studio Stitcher and tour maker, this sticher is was my favorite
but the latest version 3.0 have some serious unsolved issues.
PhotoVista Panorama easy inexpensive sticher
PanoGuide.com The source for anything Panoramic
Pano Tools very advanced freeware sticher by Helmut Dersch
VRi oneshot panorama lens
Non Panoramic Multible exposure Resources
RoundShot the original no stiching pano camera
PanoScan, the digital pano camera
Multible exposure highrez images