While working with Ethymos we came up with this new WordPress plugin that allows you to select and preview themes right from your frontend admin bar.

Here are the screenshots:

It’s a really simple plugin but we think it improves the user experience quite a bit. By clicking on the theme it will automatically preview it on the right side in real time. After that if you like what you see just click Activate and you’re all set. It is inspired on Tumblr’s way of customizing appearance and together with the new Tumblr Importer in WordPress 3.3 we’re convinced this will come in handy.

WordPress plugin for selecting theme via frontend
http://wordpress.org/extend/plugins/theme-selector/