If I'm out working you can tell that I'm a photographer even if I don't have a camera in my hand. Just look at my pants. You will usually see that the knees are abnormally worn; especially the right one. Even if my jeans are only a week old you will see a noticeable wear pattern on the knees from all my kneeling while making photos. A pair of jeans really only last me a few weeks before they are too beat up to wear anymore – just because the knees are gone. This is one reason why I don't wear Armani everyday. But why all the kneeling?
Well I think that many of us photograph makers, even a lot of professional ones, tend to make images from whatever their standing height is. For many images that works perfectly. But for others – not so much. So I get high angles when it works and low angles a whole lot. That means that I spend a fair amount of time on location crawling around and my right knee gets the most amount of abuse in the process.
Low angles have a lot of benefits: they clean up backgrounds, change perspective to that of a child/dog, make things like hands more dominant than faces which is great when your subject has expressive hands, it tends to make things heroic and then there are others which don't come to mind. Anyhoo they are not "straight" pictures which bore me. Sports photographers do a lot of low angles just because they are often photographing people who are wearing hats/helmets which obscure their eyes and sporting environments usually make very very cluttered backgrounds so the low angle shows you more face and less background.
So here is an example. I was photographing Air Force cadets performing a ceremony to honor the loss of the Space Shuttle Challenger disaster. In my usual way I got there early, great photos happen when people are preparing or in this case just standing around, and noticed how the cadets were taking turns holding the flag in a fashion that looked like a hug. The area was next to a busy street, there were loads of buildings around and the trees still don't have any leaves so the scene at eye level was not only not interesting but obscured the elements that I wanted to show clearly: the cadets and the flag. By getting in low and tight with a wide lens I got what I was seeing in my head.