Many sites have attempt to copy btctalk and even pay their visitors to post there but no one succeed. They are still a plain forum with no signature campaign in the line.
Yes I saw also other forum like a local forum but I'm quite hesitant to join like I'm thinking that it's a scam and I'm just wasting my time there. I only trust this forum and it helps me a lot since then so I must say bitcointalk.org is the best among the rest.
Actually I dont really think there is any other Bitcoin forum online apart from news sites etc. But if there is, it wont be popular and effective as Bitcointalk.org.well, maybe I should mention Reddit as a Bitcoin forum, lol, though it has to do with people from different communities.