Logging into Domains

I was wondering if there is a way to have a PC log into more than one domain. This would mean that at the Network logon dialog box there would be a drop down window to allow the user to select a domain, wether there would be 1, 2, 3, or more.
I understand that the client would haev to log off and select another domain to be able to access the resources, run a logon script, etc.