I use
Domain Name Portfolio - DomainPortfolio.us (free) to 'manage' my domains, although it does not really manage your domains you can enter the registrar and renewal dates, it creates a website that allows you to list them for sale.
It is a little clunky and as such I have not got all my domains (see footer link) into it but better than nothing I suppose.
Will be interested to follow this thread to see what others use.