I've got one CLR procedure in use, which checks drive space available on a network share before running backups. Pretty much the same functionality as xp_fixeddrives, but works on network UNC paths.

In a prior job, there was a whole set of procedures that accessed an external DLL for mailing address validation and mail list sorting. They were written using the OLE automation extended procs, but would have been much more efficient if converted to CLR. If I still worked there, I'd have converted them by now.

I've got another that I'm working on where I would normally use SSIS, but the manager here doesn't like SSIS. It will access web services, so I'll do that part in CLR.