dnsportfolio.com is a good system for a smaller portfolio. It gets a little slow for a big lot of names (or at least it used to). If you are the typical domainer with 50-2,500 names, it should work well for you. It is free although you should send $10 (or so) to the developer if you continue use it. I use the previous version (with a few mods) at Names2Buy.com.