I recently got a bit bored with my usual Clearlooks GNOME theme. I wanted something with non-rounded controls and dark blue active title bars. Here is what I came up with.

1) First I added a couple of Ubuntu GNOME theme related packages. Both are required as Mist comes from one and Gion is in the other.

2) Next customize the Mist theme as follows:

System \ Preferences \ Appearance \ Mist \ Customize...