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:
Piece of glass or perspex
Liquid in question
Green screen setup (possible to do quite cheaply)
If you want more information on the DIY solution give me a PM, otherwise there should be something floating around the net.