How do I get the full name of a user in .net MVC 3 intranet app?

You can do something like this:

using (var context = new PrincipalContext(ContextType.Domain))
{
    var principal = UserPrincipal.FindByIdentity(context, User.Identity.Name);
    var firstName = principal.GivenName;
    var lastName = principal.Surname;
}

You’ll need to add a reference to the System.DirectoryServices.AccountManagement assembly.

You can add a Razor helper like so:

@helper AccountName()
    {
        using (var context = new PrincipalContext(ContextType.Domain))
    {
        var principal = UserPrincipal.FindByIdentity(context, User.Identity.Name);
        @principal.GivenName @principal.Surname
    }
}

If you indend on doing this from the view, rather than the controller, you need to add an assembly reference to your web.config as well:

<add assembly="System.DirectoryServices.AccountManagement" />

Add that under configuration/system.web/assemblies.