Of all the places in our solar system (besides Earth) where life has a real shot at being lifeish, Europa is probably at the top of the list. This is why, in defiance of the warnings in 2010: Odyssey Two, NASA may send a pair of landers to Europa in 2020.
Our best guess is that Europa (one of the larger moons of Jupiter) is covered with a thick coat of ice, beneath which is a warm (or at least liquid) ocean. And if you've got water, and an energy source (Jupiter), all it takes is some happy little organic molecules and you've got life soup. And GIANT AQUATIC SPACE MONSTERS. Maybe.
To find out for sure, NASA is pondering a mission to Europa which would include two (two!) robotic landers. NASA figures that two is probably a good idea because landing on Europa is going to be tricky, and the radiation in such close proximity to Jupiter has a good chance of totally frying any Europa probes within just a week or two anyway. Each probe would be equipped with cameras, seismometers, and a mass spectrometer to search for organic chemicals that could signal the presence of life nearby.
I wouldn't get too excited about these landers actually discovering life on Europa. They're going to be touching down on top of the ice, and they don't have a way of getting down to the water, so it would be sort of like taking a camera to the north pole and hoping for pics of whales. They might be right there, under your feet, but you'd never know it. What's more realistic is that you could maybe sample the surface ice and find traces of whale poo (or other organics indicative of life), and that's what the landers are going to try and do.
The Europa landers are just a concept from NASA, but if funding comes through, expect a 2020 launch followed by a landing six years later.