Css2switch Basic. Since building my own Joomla template framework I won't have much use css2switch, but this well-built extension helped me out a couple of times when all other customization options had failed.
Much easier than managing multiple templates, especially if one only needs to change a few small but perhaps important structural details to particular pages. It's dead quick to slice through thorny layout issues on especially customized sites, or templates converted from client designs/HTML. I'm sure there are many other uses for the creative template designer/developer and this is a handy, easy to use tool. Chameleon. Chameleon lets your site respond to different conditions, by changing the way your site looks and acts for each one.
It's similar to a multi-site extension, except your site can respond to is much more than just domains… Simple examples: (1) use different template for mobile/tablet devices. (2) change branding/menus on your site for visitors coming from an affiliate or from a different country (GeoIP). You simply set up "conditions" to be detected, plus the "actions" to be performed when the conditions are met. Chameleon does the rest! What can Chameleon detect? Template Creator CK.