Using intervalometers to create time-lapse photography is more of a research tool than it is for artistic expressions, but both can coincide, and often do. Time-lapse allows us to see things beyond the basic perspective of human perception. Much like the eye can only see visible light, but we all know that that range extends far beyond that, into the IR and UV areas of the spectrum. Time-lapse imagery allows us to see into the IR portion of the temporal (time) spectrum, conversely, ultra high-speed videography allows us to see into the UV portion of the temporal spectrum.
That being said, the uses for an intervalometer for photography are varied and many. Watch any nature special and you'll see how a seed sprouts into a mature plant; how a fungus fruits into a mushroom; how a slime-mold will crawl with its million of amoeba-like cells across a log and eventually form into fruiting stalks; or the most common time-lapse video clip, the opening of a flower. When watching video-clips of growing plants, you'll often see them swing side to side during any 24 hour period, this revealed the aspects of plant-growth and plant-behavior now known as phototropism and eventually the chemicals that cause this in plants.
Did you ever see something hours, days, or weeks later that has changed shape, position, color, size, or other attribute and wonder to yourself, "How did it do that?" Now you have a means of discovering the answers to that question.
If looking for possible subjects to capture for time-lapse video events, you need only ask yourself that simple question.
And who knows, the very most simplest thing that all others have always taken for granted, could just lead to a whole new branch of science. Just because you noticed something and became curious about it, enough to capture it in a time-lapse sequence. But if you do, please pay attention to composition as well. I wish more researchers would take artistic values into account.
"Discovery consists of seeing what everybody has seen and thinking what nobody has thought." - Albert von Szent-Gyorgyi