I've met quite a few, but I'm not sure where to divide the line between "met" and "know".
I think I'll define "know" as those who have either been to my home or I have been to theirs:
Piratecat & KidCthulhu (Spent 3 days at their home)
Mark (OK, I only saw his apartment for about half an hour, but we hung out in Chicago for a few days; speak to him by phone occasionally)
Liquide (He moved into my home for a month!

)
Ravellion (He has visited me twice, although the second time he just spent 3 days planted in front of the Playstation 2...)
Tallarn (Visited me once)
Alshi20 (One flying visit)
Scaragoth (Visited me once)
Then there are those who I consider myself to "know" just from meeting at conventions etc., but had previously gotten to know (and like) pretty well online:
Eric (duh!)
Rangerwickett (owes me $4.85)
Nemmerle
Adlon (met at Gen Con, speak to on the phone now and then)
Dinkeldog (although I think I know him better now than when I met him in Chicago)
Hellhound & Dextra (met very briefly at Gen Con, but getting to know better now with EN Publishing)
I've "met" lots of people - far too many to list. And I'm sure I've missed at least somebody off the above lists - if so, I apologise!
Oh, of course I also know Inconsequenti-AL, who has only posted about twice but who lives round the corner from me.