Hi
I'm a member. OBC stands for old baseball cards, you can find more information here
http://www.oldbaseball.com/obcfaq.html
Yes, although I think most of the folks in OBC concentrate on 50s/60s there are quite a few pre-war collectors who are also members of this forum.
Its kinda a trading club, but really more than that. The FAQ should cover everything, but a key component is RAOK (random acts of kindness). One day you go to your mailbox and surprise a 1964 Willie Mays or a T206 SL, or more likely a handful of 1972 commons. Another key component is what comes around goes around, you may hit my wantlist and I might not be able to hit yours, but I can hit Joe's etc.
Its not for everybody, but if you are looking to complete some 60-70's sets in VG- condition or if some of the seedier aspects (greed, shill bidding, selling reprints for genuine, etc.) of the hobby are bothering you then you should check them out. Joining OBC may be for you.
thanks
Bob