Can I change my OS X theme? Some of my friends said that OS X sucks because you only have to choose one theme on every device that have OS X. I searched, but I didn't find any feasible solution just one little thing that cost money (and I didn't want to risk it). 

Is there a easy way to change OS X themes that is free? Please don't tell me that the theme doesn't need to be changed; I really want something like Ubuntu that can change anything, I really love my Ubuntu desktop (KDE and Gnome).

If OS X doesn't do this, are there any 3rd-party utilities that can?
Out of the box there is no themeing capability in Mac OS X, you can however modify some of the colours used by Mac OS X in the Appearance Preference Pane in System Preferences.

If you're serious about themeing however there are 3rd party applications you can get to help with this:


CandyBar - manages and changes icons.
ThemePark - does most everything else. If you're interested in available themes that work with ThemePark check out MacThemes


Otherwise a fairly good resource is the forum at MacThemes.