Apple have made it possible for developers to issue demo codes for their iPhone apps.

http://www.macrumors.com/2008/12/02/developers-can-now-issue-free-promotional-copies-of-iphone-apps/

While this is a good first step it falls short of what is really needed. For a start the codes can only be redeemed in the US iTunes store.

Secondly, what is really needed is a method of offering a free trial, along with the possibly of in app purchase of the full title.

Perhaps if people could try before they buy the pricing race to the bottom in the AppStore could be arrested.