My choice of holders:
Mobile iPod Docking Kit (Black) | Bracketron
(It holds the Evo "naked", or with a case)

To go from portrait to landscape at the flick of a wrist, add the swivel mount:
Ultra Slim Swivel | Bracketron

This is in my dakota R/T; here is a vertical pic:



And a landscape pic:



Hope this info helps; you can find both of these on ebay.

 

I'm using a bracketron bracket and use the swivel that came with mine. You can get them pretty cheap though. You can see the setup in this thread... hope it helps.