Obviously, there are other focal lengths available for every format. Lenses with a focal length longer than normal are called telephoto or long lenses. These lenses have a narrower angle of coverage, shallower depth of field, and close focus at further distances. Most fisheye lenses do not correct for horizontal or vertical abberations, causing straight lines to become curves and distorting perspective. There are, however, high-end fisheyes that do have perspective correction built into them.
Zoom lenses have a range of focal lengths available in one lens.
Zoom lenses generally don't have the range of f-stops that fixed focal length lenses do, but make up for it in versitality. Because the focal length is relative to the size of the film, lenses are not interchangeable between formats. You must use a lens designed for your particular format or suffer vingetting from using a smaller format lens, or flare and low contrast due to a lens designed for a larger format. A lens's relativity to film format also means that a particular focal length will not have the same angle of coverage from one format to another. Below is a chart listing the common film formats and the degree of coverage provided by a particular focal length lens appropriate to each format.