Marter said:
It's nice, and I have quite a few, but I've found it's very easy to fall out of touch with them. And that's never fun.
This, with most of the people I played WoW with for 2 years.
I was really close to about half of my guild that I raided all of wotlk with, but as we got disillusioned with WoW, dealt with drama, quit for other games, we just sort of lost touch.
I still try to keep in contact with everyone I can via battle.net when I am on SC2, but so many old friends have quit Blizzard games completely (at least until D3 comes out).
One of my closest friends is a guy I met on WoW via an IRL friend, that I play xbox with all the time. He's like another me, but American.
I think online friends allow you to be more yourself (or less yourself if you are so inclined) and are great to have, but it gets dangerous when you want to meet said friends IRL. They may not be as funny as they were online, may not be as young as they told you were, or be a dude when they said they were a chick... Obviously these horror stories are grossly exaggerated, but that doesn't make them completely false.
I spend most of my time online away from normal humans, so I have a lot of online friends.
Even most of my IRL friends have turned into online friends that I only talk to online, because of work/moved away/etc.