eBay announced yesterday that they are making the use of their APIs free. This removes their previously existing fees ranging from $1.25 to $2.90 per 1,000 items listed and a $500 annual fee.
They have a well established and sizable developer's program with over 21,000 developers who've created over 1,600 applications on on eBay's auction network. And we're not talking maps mashups here -- as the NY Times noted yesterday, 22 percent of eBay listings are placed there by third-party programs using the the eBay APIs. Developers aren't just small players either and include SAP, Verizon and EarthLink. They support some 2.5 billion API calls per month. Not small potatoes.
In addition, eBay has also just kicked-off the eBay Developer Challenge 2006 where you could win $5,000 (individual) or as a team create an open source application and win a set of matching Xbox 360 game consoles. They lead by pointing out that in 1995 the basic idea of what became eBay was codding in a weekend and ask "So, what can you do in a weekend?"