In updating some API database entries I finally had the chance to dig deeper into Syndic8. Very useful content syndication service that was really a bit ahead of time back when it started in 2001. The site and service do a variety of things but the real focus a clearing house for feeds. They have about 15,000 registered users 450,000 feeds. And it has an nice API.
The API has a well documented XML-RPC interface. It also has one thing I'd not seen elsewhere, a statistical summary of the incoming web services calls serviced (scroll to the bottom of that page to see). Interesting to see the distribution -- the major service providers don't tend to share their exact usage numbers -- only Google knows which of their APIs get used most frequently.
Jeff Barr who started and still runs the site now keeps busy as evangelist for Amazon's Web Services team. See him interviewed here when Scoble goes to Amazon and Learns All About Web Services.