I say you can, although I also think that there will always be an aspects of a person that can never be fully conveyed through online interaction, i.e. particular mannerisms, certain elements of someone's personality, etc.. I certainly made a couple good friends online, and they have made me feel special and cared about. I guess it varies from person to person, though.
I think, though, that you have to be aware that in some cases it's easy to project your own ideas of what a person is like onto that person, when you're just interacting with them through a computer screen. I know I've probably been guilty of doing it (although unconsciously so) in the past, with people I've chatted to; I have no doubt that I did know their personalities quite well, but no doubt my imagination still embellished the overall picture I had of them to a great extent.
