Hi George,for services rest you can use Windows Authenthication so you use local user or domain user or sql server (express) that user Membership asp.net ( http://msdn.microsoft.com/it-it/library/cc185055.aspx) or custom provider.If you use Windows Authentication you don't use token but in proxy (get proxy_net.zip esri) you set credential in webrequest like:
HttpWebRequest req = (HttpWebRequest)WebRequest.Create("...");
req.Credentials = new NetworkCredential("myLogin", "myPwd","mydomain");
if you set scheme membership asp.net from Manager arcgis in example sql express (manager creata also db) you can create user and role in sql express. Then you set from manager privileges on service or folder arcgis using roles and then you use token for users.Info on privileges for service are store in file .sec where you have cfg of services.if you use Windows Authentication remembers that in iis remove anonymous authentication if you want do access page rest from windows authenthication user that you have set in Manager (using roles: group of windows) and enabled windows authenthication.