Does it have to be influenced by anything ingame? If I was doing it I'd look for dripping animated textures online and then make it into a semi-transparent sprite.
You can make this texture yourself with the following tools:
Video Camera
Piece of glass or perspex
Liquid in question
Green screen setup (possible to do quite cheaply)
Compositing program
If you want more information on the DIY solution give me a PM, otherwise there should be something floating around the net.