Titan has a methane cycle.
Lost lakes of Titan are found at last Wed Jan 3, 2:35 PM ET
"They believe the lakes prove that Titan has a "methane cycle" -- a system that is like the water cycle on Earth, in which the liquid evaporates, cools and condenses and then falls as rain, replenishing the surface liquid."
http://news.yahoo.com/s/afp/20070103/sc_afp/spacesaturntitan_070103193516