syfluid
Fancy interactive fluid simulation for gfx fans, VJs and demo coders
.... "s" to save a png or jpg.
syfluid is written in C++ using OpenGL. Even though it is heavily performance optimized and using OpenGL Shading Language (GLSL), it is a performance hog. Use "f" to show the FPS. If they are lower than 30, then reduce the quality parameter that you find in the menu from 200 to e.g. 100. For very fast graphic cards, try 400 and above.
This fluid simulation is based on on Jos Stam's paper:
http://www.dgp.toronto.edu/people/stam/reality/Research/pdf/GDC03.pdf