ContactZilla allows you to import contacts from Twitter, LinkedIn and Google, as well as manually enter information about people one-by-one.
The app comes from a Web development firm called Simpleweb, who say they are "massively supportive" of open standards and data portability. As such, contacts can be easily exported from ContactZilla and they're always adding support for other data sources. In addition to Twitter, LinkedIn and Google, users can also pull contacts from Basecamp, FreshBooks, Outlook, vCards or any CSV file.
Once contacts from multiple sources are loaded, they are then automatically cross-referenced, merged and cleaned up. If they're available, avatars for each contact are pulled in from sources like Twitter and Google.
"The focus has been on getting in contacts from various sources, de-duping them based on 'personal unique fields' such as email address, Twitter address, mobile number, etc," Simpleweb cofounder Mark Panay told us via email. "We then try to discover more of these fields based on existing ones using various social graph techniques and then re-apply the de-duping algorithm."
This de-duping process is pretty good, but it has its imperfections. For example, people from Gmail that have multiple email addresses will be imported as separate contacts. This, of course, has to do with the limited data points available from each source, but it seems as though two contacts having the same exact name (or same avatar image filename) should trigger some kind of flag.
After a TechCrunch post brought their Web server to its knees last month, ContactZilla is now up and running again, and preparing a new release in early March.
Among the new features planned for the new release are "smart lists" for breaking down contacts by various criteria, some user interface updates and an API that's compliant with the Portable Contacts standard.
If you're interested in giving it a try, you can sign up using the invite code rwwcz. There are only 200 invite codes, so hop to it.