Listrak is an email marketing company solely focused on the ecommerce channel. By getting to know their clients in depth, reviewing clickstream data and transactional history, and plotting customers on a lifecycle grid, Listrak is focused on delivering two things, according to CEO Ross Kramer, "help our customers acquire more new customers, and sell more to existing customers." The Listrak SOAP API makes automation of managing email campaigns easier.
Developers with a penchant for green-energy powered APIs should probably take a look at GreenQloud's IaaS offerings that are API-compatible with Amazon's EC2 and S3 services. The Icelandic company's datacenters survive on nothing but 100 percent renewable energy.