GUI design, look, feel,

I'm looking for some GUI design ideas.  Screenshots or perhaps even LookandFeel classes would be great. Does anybody knows where to get such stuff?

I don't, but think it would be a great resource to have some good examples of different kinds of look and feel designs. For now the different LnF classes are a good reference. 

I'm using Windows and I just recently started with OSX. I like how it looks and I would like to create this look on Windows and on Linux.