I used to use a 'sock' type thing... which offered NO form of protection.
Then I bought the official HTC pouch , which was good, but still, no protection when using the phone.
Then I purchased the Otterbox Commuter from Amazon for a tenner... It's brilliant. One thing I would say is that the screen protector it comes with is a bit 'plasticy' , and I'm looking to get a PhoneDevil protector soon.