Big Money question here
 

Although I've seen that Crossover Studio can run Macromedia Dreamweaver (and Flash I think), does anyone know if there is an open source application like Macromedia Flash?

I think I know the answer to this one, but I was wondering if there is anything I've overlooked.

None really. But you can probably get Flash working by using wine.
Good site for getting apps to work with wine is www.frankscorner.org

The only official flash from macromedia for Linux is the plugin for browsers.

Cheers.

It would be better if you tell us what you want to do exactly...

and just a heads up for the future, there is a project in development
called flash for linux located here
so you may just want to watch the progress on it, as it may turn out to be a success if they get more developers ...
and maybe if you just do the simple stuff this app may suffice ..