I'm guessing most people either don't bother with it (I haven't...) or write their own ad-hoc file integrity managers using checksum files and par2. I was about to try something, but decided to go look for existing work instead.

There's a proliferation of backup software, but this is the only file integrity solution I've come across. Surprising, since file integrity is the only way to know if what's being backed up is any good.[0]

[0] http://www.taobackup.com/integrity.html