Would you please like to tell us how did you do that? I've invested piles of money in adwords yet didnt earned more than 3$ in a week.
having taken a look at your sites i can't understand how you got the traffic without asking people to click? just my feeling cause the sites dont really have any interesting content...
IMO people generally don't include their best sites in their signature because people will just try & copy them
That is what I am thinking Did you use promotion or just let the site hang and visitors found their own way?
congrats, I'm aiming to do the same as you with my site, I just dont know what to write in a blog to get traffic, seems impossible to me...
Congratz, but dont stop working on improving your sites and adding content to them or they will quickly start lowering visitors. Gaining a good respeat visitor ratio can be good in the long term, but may not necessarily increase revenue from adsense itself.
Too many questions here... here's the most important: where is your traffic from? how much do you spend on promoting(if you do)? good job anyway