How can I make a site like this fluther.com web 2.0-looking site?

Read these articles.. http://blog.fluther.com/blog/category/howd-they-do-that/

If that looks totally foreign to you might want to set your sights a little lower.

You could try to have a site that has a one-click installer for PHPBB to make a forum. Bluehost makes it pretty easy to set up one up. Or you could use http://Wordpress.com to set up a blog and start trying to get that to fit into what you want to do.

But you would need a significant knowledge to recreate Fluther. If you know HTML, CSS, Javascript, MySQL, and PHP or Ruby, or Perl, or Python. It wouldn’t be insanely hard. Just really time consuming. (Get my drift?)

@johnpowell: Don’t forget hiring a designer!

That helps too.