As I mentioned in my earlier post on Sublime Text 2 color schemes, I had grown tired of trying to find the right color scheme and switching manually in ST2 is not very fun. Themes in ST2 actually affect the UI of Sublime Text. The sidebar color, appearance of tabs and folder icons etc are all controlled by a Sublime Text 2 theme. There are several different themes out there but these seem to be the most prevalent right now.
If the theme comes with different color schemes then I have usually enabled those with the theme. I kept the light and dark color schemes and themes together because they generally look better but that may be my personal preference. Browse through, enable your favorite and start joyously coding / writing away.
Note: I've put the theme name first and the color scheme name second separated by a dash.