Foundation DB
http://techcrunch.com/2015/03/24/apple-acquires-durable-data...
"Apple has acquired FoundationDB, a company that specializes in speedy, durable NoSQL databases, TechCrunch has learned.
A notice on the FoundationDB site notes that it’s no longer offering downloads of its database software. "
Granted, Apple doesn't acquire at Google's or Facebook's rate, so the sample size is smaller
What Free service has Apple shut down? Their major that's been around for a while is iCloud/etc, which before was MobileMe, which before was .Mac, which before was iTools.
I don't know the technical details of how those back-end services relate to each other (i.e. evolution from one to the next, being rebranded, or re-built from scratch each time, etc) but there are very few things that they've truly shut down.
For a while after MobileMe and before some of the major improvements to iCloud, Keychain sync was not available, but I'm struggling to think of free services they've actually shut down.