Sharepoint Feature : Update the web.config

What will you do when you need to update the web.config from a feature?
The first thought will be to read the xml. 
Please don't go through the pain, simply follow me for a few more lines where I'll increase the truset level to Full in web.config

In the feature activated method, Use SPWebConfigModification

public override void FeatureActivated(SPFeatureReceiverProperties properties)
        {
    // Obtain Site
            SPSite site = properties.Feature.Parent as SPSite;
    // Obtain Web application
            SPWebApplication webApp = site.WebApplication;
            System.Collections.ObjectModel.Collection allModifications = webApp.WebConfigModifications;
           // Specify the node
            SPWebConfigModification myModification = new SPWebConfigModification("level", "configuration/system.web/trust");
 // And the custom value, finally !
            myModification.Value = "Full"; // the value of the item to set.

 // owner of the web.config modification
 myModification.Owner = strUserName; 
// Sequence number the modification if more than one modification to be done increase this by one in each modification
          myModification.Sequence = 1; 
          myModification.Type = SPWebConfigModification.SPWebConfigModificationType.EnsureAttribute; 
       
 allModifications.Add(myModification);
         SPFarm.Local.Services.GetValue().ApplyWebConfigModifications();
         webApp.Update(); 
            
        }

I hope, it'll save some time of yours.