Any cool incentives to get more members?

[Xipher]

Excellent sum up. I would like to add a few things.

Focus your site on something, and have the site design kinda imply that focus.
Keep your site colors in check. No one wants to try and read red text with a green background.
As and admin, it is almost critical for you to be active, and you will be starting forum topics a lot on your own. Just try to come up with some catchy topic titles.
One thing I have learned is DO NOT hide your whole forum to guests. This will more then likely run them off, seeing as they cannot even see your board.

That is all I can think of off the top of my head. If I remember anymore, I will edit them in.

Good Luck!