what type of "domain"? an internet domain? that's easy, read about using host headers in IIS. go
here
an active directory domain? not possible on a single server. an active directory domain requires a domain controller for each domain. you could setup additional domain controllers as child domains of the existing parent domain.
for example:
current domain -- foo.com
new child domain -- big.foo.com
each domain will have to be hosted by separate domain controllers.