I have been using Clojure to make API's that talk to IBMi servers.
Clojure is nice because it interops nicely with Java, so it can access the IBMi via the JT400 toolkit.
I do a lot of support for various clients running IBMi servers. There are many troubleshooting exercises that I used to have to do manually, serially and asynchronously. Connect to a client, run a report, scan the results, check a constant here, check a constant there - verify certain jobs are running and have no messages etc.
I can now point my browser at an URL, and my Clojure program will run the whole troubleshooting tree, and present me a webpage showing me all of the results. Often I can even include a "Fix it button" next to the problems.
If you are interested, here is a pretty bare bones starter gist: