There is interesting article called Where The Affordable Homes Are [BW]  that provides suggestions on how to find affordable housing and what to focus on.
The article contends that if we are truly at the peak, “the risk is high risk that you’ll get zero or negative returns on your investment over the next few years” so you should focus on affordability (and therefore stay away from the coast line) and there are plenty of options.
The premise of the article largely depends the buyer’s flexibility to move anywhere in the country for the sake of affordable housing.
One of the problems with these options for many consumers is simply the reason these housing options are cheaper to begin with. The income potential in many of these areas is lower which keeps housing prices down. Career opportunities could be more limited. Areas on the fringe that require a 2 1/2 hour commutes often see limited appreciation because its more difficult to find buyers for properties in these areas. Quite often, the employment base is weaker and opportunities for someone to pack up and move to a new job in that area are more remote (no pun intended).
Today’s New York Times had a real estate article called What You Can Get for $220,000  that took a different tact. In a housing market like New York, which is among the most expensive in the US, the article covered the options to buyers to find housing that was priced at about the national median sales price for US housing at the moment, as defined by the National Association of Realtors (ok, ok I was quoted in this one).
Resources to find an affordable markets
3Q 05 Existing Home Sales [NAR pdf] 
House Valuations In Major US Metro Areas [National City pdf]