Do your GTK applications (i.e. Firefox) look like something designed in the 90’s in KDE? I think I can help you.
I installed the latest Firefox, (not the one in the screenshot, I stole this.) and was very disappointed to see something like the following:
Tyler pointed me to the Gentoo guide here, which helped me find out which packages I needed.
If you install Chakra-Gtk-Config, and either oxygen-gtk or qtcurve (make sure to download the gtk2 theme), you will have better looking GTK applications in no time. Note that there are probably tons of other GTK themes for KDE4, these are just some suggestions to get you started.
That is much better.
After playing with the GNOME Appearance preferences on my new Mint 8 installation, I managed to completely lose the color scheme, window decorators and other options for the default Helena theme – which I actually liked.
Due to an unrelated incident that I will blame on an abuse of Compiz (which really doesn’t play nice with the Xinerama extension), I recreated my GNOME profile this morning and saved out the default theme. For my own future reference (and anyone else who doesn’t want to nuke their profile), I’ve uploaded the default Mint 8 theme. Extract it to your ~/.themes/ directory and it will appear in Control Center > Appearance as “Default Mint Theme”.
This theme should theoretically work on any Linux distribution with GNOME, as well, but you’ll need the “Shiki-Wise” control set, “Shiki-Colors-Metacity” window border, and the “GNOME-Wise” icon set for more than just the gray and green hues.