Liquid in motion sounds great.
Some other ideas for the future:
Natural light portrait (can use reflectors but no flash)
Shadows (where the subject of the shot is the shadow of the object instead of the object itself)
Reflections (in anything - water, mirrors, shiny objects)
Freeze frame (stopping rapid movement, especially movement not normally seen with the naked eye)
Sorry....what was the question again?
PPOK - as long as you tell me what you did to fix my dodgy image!