Mashups [1] and Extract Transform Load (ETL) [2] are two big use cases. I developed a freelance project aggregator using an earlier version of riko [3].

[1] http://mashable.com/2009/10/08/top-mashups/#0XwtqVCCXPq2

[2] https://www.quora.com/How-do-ETL-tools-work

[3] http://app.kazeeki.com/

Thanks, appreciate your comment.