Here is section of code that can list all AppDomain of the current process

using System.Runtime.InteropServices;       // for domain enum
using mscoree;                              // for domain enum. Add the following as a COM reference - C:\WINDOWS\Microsoft.NET\Framework\vXXXXXX\mscoree.tlb
namespace MyNS
{

    public class ListProcessAppDomains
    {
        public static IList GetAppDomains()
        {
            IList _IList = new List();
            IntPtr enumHandle = IntPtr.Zero;
            CorRuntimeHostClass host = new mscoree.CorRuntimeHostClass();
            try
            {
                host.EnumDomains(out enumHandle);
                object domain = null;
                while (true)
                {
                    host.NextDomain(enumHandle, out domain);
                    if (domain == null) break;
                    AppDomain appDomain = (AppDomain)domain;
                    _IList.Add(appDomain);
                }
                return _IList;
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
                return null;
            }
            finally
            {
                host.CloseEnum(enumHandle);
                Marshal.ReleaseComObject(host);
            }
        }
    }
}
</pre>