My definition of a friend, online or otherwise, is as follows:
A friend is someone who is there for you. You may never meet your online friends, but still, if you post a blog, they read it and leave a comment. They feel your pain from thousands of miles away. They chat with you. They share with you.
A friend doesn't put another friend down. Gee, that one seems kind of obvious. If one day you're called a friend and the next day you're called an asshole by the same person, then really, is that someone you want to associate with? How can anyone trust a friendship like that? A friend is a friend to the end. They don't go off and start posting untrue crap about you just feed their own self-importance and/or ego.
A friend doesn't put you on the defensive. To have to defend your honor or honesty because of so-called crap is ridiculous.
I have many wonderful friends on the LC, Yahoo and other online venues. Some near, some far away.
If they can't be a true friend, then they can be gone.... their loss. Seems pretty simple to me.
Karen