http://dnlisting.com

I created this site because I had a hard time keeping track of the domains I owned and a spreadsheet wasn't cutting it.

It offers a simple means to organize your domains and allow other domainers to see the domains you own.

The service is free, there is a bulk domain addition tool (25 at a time) to easily setup your listing.
In addition, single and bulk domain adding automatically finds the registrar and expiration date for the domains.

Here's my listing: http://dnlisting.com/Unknown

Note to Mods: Wasn't sure where to post this since it not a domain name offer