There are only a handful of places in the Solar System where we think it might be possible to discover life. Although it seems like the Earth is the only place in the universe teeming with organisms, there is a chance that we might find other life forms right here in our own spatial back yard.
Scientists are just foaming at the mouth right now with the idea of searching some of the Solar System's likely life-supporting candidates. Among those are some of the moons orbiting Jupiter and Saturn, such as Europa, Ganymede, Enceladus, and Titan.
Almost all of the aforementioned moons have sub-surface oceans, except for Titan, which has surface oceans of methane. Worthy of note, Ganymede is the only moon in the Solar System that's known to have a magnetic field like the Earth's, and Titan has a rich atmosphere.
Enceladus may be out best chance, as it is believed to have hydrothermal vents like those on the floors of our oceans, and they're crawling with critters here - so why not there?
Keep in mind, these potentially life-supporting places are all in our own Solar System, and there are many other systems in our galaxy, as well as several other galaxies throughout the universe. Chances are there is more life out there, somewhere, but where and when we'll find it is another question altogether.