Update - Adding iTerm2 Themes

The previous post became outdated when newer versions of iTerm2 updated the Preferences UI, so this post is meant to cover iTerm2 version 1.0 (and newer).

The iTerm2 Color Gallery page is the centralized repository for iTerm2 themes and provides links to available themes if you want to know where to go to find iTerm2 themes, (although most of the links will take you either to the author's personal site or to GitHub).  If you find a theme you like, download it or save it as a text file somewhere.

To manage your installed iTerm2 themes, click the iTerm menu and then the Preferences... menu item.  Click on the Profiles preference category and then the Colors tab.  A window like the one below will be displayed:

There is a drop down at the bottom of this tab labeled Load Presets....  This is where you will go to install or remove iTerm2 themes.  

To install an iTerm2 theme, click the Import... command from the Load Presets... drop down list and then select the file you downloaded from the Color Gallery.  It will then be available in the list of available themes, separated from the five system themes that ship with a default iTerm2 install (Dark Background, Light Background, Pastel, Tango Dark, and Tango Light).  

To uninstall or remove a previously installed theme, click the Delete Preset... command from the Load Presets... drop down list.  A drop down list of all the themes that you've imported will display and you can then select the theme you'd like to delete.  Please note that you can not delete the five system themes that ship with iTerm2.