For .com and .net domains...check NSI Registry for registry/registrar data of domains.
http://www.nsiregistry.com/
On an aside, note the expiration date shown at the registry does NOT necessarily correspond to the actual expiration date of the domain at the registrar. An example is when a domain name expires at the registrar, but the registrar doesn't delete it right away...the .com/.net registry after a period of time automatically adds another year on - it's credited back later in a matter of speaking, but anyways this is a quirk one has to be aware of when checking the registry directly.
Bottom line is one must manually keep track of domain name expiration dates and continuously monitor their domains - some registrars send zillions of notices, including some by mail, and even call...GoDaddy is a deep discounter and basically zaps domains when expired...great for bulk registrations of mediocre domains, but for anything important, one may do better elsewhere.
Ron