First follow the steps to create a console application for working with SharePoint 2007 Social Computing features

Now that you have your application ready to go you can display users that already have a MySite using the code below.

Display Users that have a MySite

//Get the site associated with the users
using (SPSite spSite = new SPSite(@http://localhost))
{
   //Create the server context because you are in a console application
   ServerContext siteContext = ServerContext.GetContext(spSite);
   UserProfileManager pmManager = new UserProfileManager(siteContext);
   foreach (UserProfile spUser in pmManager)
   {
      if (spUser.PersonalSite != null)
      { 
         using(SPSite personalSite = spUser.PersonalSite)
         {
            //Use SPSite like a normal site
            Console.WriteLine("personalSite.Url: " + personalSite.Url); 
          }
      }
   }
}

You can see that once you have the site you could use it to check document libraries or any other action you would perform on an SPSite.

Addition Resources

For an in-depth look at the API and programmatically using the Social Computing features of SharePoint 2007 check out chapter 8 of Professional SharePoint 2007 Development