I think there has to be some sort of life outside of earth, we haven't even searched everywhere in our galaxy, much less the entire universe. Its hard to say what we would find though, it could be anything from bacteria to something straight out of a movie or game. What I personally think is that it's possible that (in descending order of craziness):
1. We along with the other aliens haven't developed enough to communicate or make contact with eachother
2. We aren't advanced enough for aliens to take notice in us
3. Aliens tried to make contact in the past but we blew it

4. Aliens living among us :ninja:
I doubt we'll find out in our lifetimes though