I have been involved in several UFO investigations through the American/Canadian skeptic organization JREF which I have been a member of for aprox. a decade or so. I do believe there are E.T.'s out there, but I'm not convinced they have made any sort of contact as of yet.
I used to study philosophy of science, and that's why I engaged in the UFO research. Provided we had more than hearsay and at least a few bits of hard evidence to work with tho. Especially one case took my breath away for about 6 months: It was a publication by the Mexican govt., where they claimed to have been taping genuine UFOs through airforce equipment. Well, they were indeed unidentified flying objects, although, after months of research, we could conclude that they were grounded. So it turned into a UGO case (meh).
I talked to the Mexicans, and asked not only for a copy of the full tape, but also the rights to publish it on the internet for all to see. They agreed.
My conclusion became this theorem..
We spent 6 months chasing oilrigs in the Mexican gulf, because as the former chief engineer of FLIR systems inc. (those who made the IR camera in question) told me, then I should take contact to the Danish navy if I wanted to see how to operate the camera used "properly". Oh boy.
That's the most convincing UFO case I have/had ever seen tho, and I'm still not convinced that any sort of contact has been made.