Dmitry,
Sounds like PS or Tranny fluid.
Is the puddle large or just a few drops?
Have you noticed any change in fluid levels?
How about performance changes? Stiff steering or hard shifting?

Just some things to consider while tracking down the nasty leak....

------------------
William
76 240D (W115) - 550K miles
78 300D (W123) - 200K+ miles