My initial interest in time-lapse photography began with making movies of a midwestern geek's annual trek to Gen Con, which had recently moved to Indianapolis. This was conspicuously less convenient than Milwaukee, but did provide the opportunity for longer and more interesting movies. Eventually I put up a webpage about the process, including refinements made in subsequent years. With the success of that endeavor, despite fairly primitive equipment and no prior practical experience, I have expanded my interest in the genre. The page on pool construction contains three time-lapse movies of tradesmen to illustrate other applications of time-lapse photography.
The whole point of time-lapse photography of course is to speed things up. Although different interesting processes happen at different speeds, the unaided human is only fit to examine a small fraction of those, the ones which occur on time scales between approximately 100ms and 10 hours. That's a remarkably wide range, over 5.5 orders of magnitude, but still leaves many changes outside the range of our perception on the short end and attention span on the long. The lure of time-lapse photography is that it reveals intriguing new things with a minimum of investment. The time of course must be spent, but only by the camera, not by me. The equipment consists (if one is to do this digitally) of a low-end camera, a low-end computer, and an amount of disk space which, as of 2007, can only be described as "trivial". I go into more detail about the hardware required on the page I referenced earlier and shan't repeat myself here. Suffice it to say that making slow things seem fast is a lot cheaper than making fast things seem slow. The results of making fast things slow can be quite striking, of course.
A cheap digital camera, coupled with Canon's free software, will allow the taking of individual pictures at up to 0.2fps, for up to 9999 frames. When played back at 30fps, this gives a minimum speed-up factor of 150x, which sounds incredibly fast (it compresses an hour into 24 seconds). However, a factor of 150 is less than 2.2 orders of magnitude, not all that much in the scheme of things.