~ 3 months in: We used some "unconventional methods" (that I won't mention in detail) to attract a few initial users.
~ 7 months in: We had a breakthrough with google (we still aren't sure exactly what it was) and we started to get a ton of search traffic
~ 10 months in: from here, traffic was all from word of mouth and referrals. This was by far the major segment. The first two combined up to maybe 40,000 users...everything from there to 300,000 was primarily driven by word of mouth
After that we had some deals, etc, but most of it was just surviving until things picked up on their own.
I can tell you that we tried anything and everything to get even a little bit of attention in those days. I can't point back to one thing and say "that's what really got it started"...I think it was just a combination of keeping ourselves out there until we were in the right place at the right time.
And now I have to do it all again.