I don't think Area-51 was some sort of alien base or anything, but I do believe Aliens exist, not necessarilly that they are visiting us, but they have to exist. There are literally billions of stars out there and if our sun is the only one with a planet capable of sustaining intelligent life then it is a big waste of space.
Also, I do tend to believe that aliens are watching us and possibly visiting our planet. Something happened at Roswell, something happened in Rendelsham Forest, and then there is the story that scared the hell out of me when I was little and I still find to be the most interesting, the Varginha incident. Are all these alien crash landings? I don't know, but something happened there that these government don't want us to know about.
Even though we don't know for sure how they got there, the fact is that people were present in the Americas before the first Europeans landed and some of these civilizations were in their own ways far more advanced than the Europeans, is it not possible that the same could be true but on a galactic scale?
Please note that 98% of what I say is my opinion and/or my "version" of the facts. Most of what I say is rumor with little to no evidence to back it up, just something I picked up somewhere.