GetDisplayNameFor<MyType>(x=>x.MyProperty);

DisplayNameHelper.cs

public class DisplayNameHelper
{
    /// <summary>
    /// Get the DataAnnotation attributed DisplayName attribute value.
    ///  </summary>
    /// <example>
    ///  GetDisplayNameFor&lt;VagtTyper&gt;(x =&gt; x.Doegnvagt) ==&gt; "Døgnvagt"
    /// </example>
    /// <typeparam name="TSource">The type you wish to work on</typeparam>
    /// <typeparam name="TProp">The type of the property</typeparam>
    /// <param name="propLambda">Property selector for that type</param>
    /// <returns>The DisplayName or the propertyname if no DisplayNameAttribute was set</returns>
    public string GetDisplayNameFor<TSource, TProp>(Expression<Func<TSource, TProp>> propLambda)
    {
        var member = propLambda.Body as MemberExpression;
        if (member == null) throw new ArgumentException("No methods, please!");

        var propertyInfo = member.Member as PropertyInfo;
        if (propertyInfo == null) throw new ArgumentException("No fields, please!");

        var dna = propertyInfo
            .GetCustomAttributes(typeof(DisplayNameAttribute), true)
            .OfType<DisplayNameAttribute>()
            .FirstOrDefault();

        return dna == null ? propertyInfo.Name : dna.DisplayName;
    }
}