Most real estate agents will refuse to do this for you with a POA because of the tremendous liability that comes with it. Many companies have company policies that forbid the agents from acting with POAs because of the liability involved.
Another option if you are looking for foreclosure or investment property are HUD homes. You can have a real estate agent that is registerd with HUD bid on properties for you while you are out of state. Most everything can be taken care of via fax or e-mail.
Visit http://www.hudpemco.com to search for HUD properties.
I'm a registered HUD Agent and would be happy to assist you if you find any properties you would like to bid on.
Just so I understand, why do you want to buy a house out of state? Is this for investment or are you moving?
Foreclosures are buyer beware in my state. Are you talking about a foreclosure auction or regular auction?
If it is a regular auction, the rules on how to bid are set by the auctioneer and the seller. You may be able to particpate over the telephone.