Most of my time is around vehicles, especially motorsport and I do enjoy motorsport photography, but I cant limit myself to a single type of photography as since I bought the SLR, I feel compelled to have a go at everything.
I would say though to narrow it down so recommendations can be given my main areas would be
Motorsport - soon to try aircraft
Static/Wide angle (anything from landscapes to car shows)
Portraits - I spend a lot of time photographing my nephew
