Imagine my happiness:
SELECT * FROM sys.dm_exec_procedure_stats
Extra credit: join to sys.procedures (also new) to get the object.
So, now you can see, since the server was started, what runs. And since your server stays up for several months at a time, you have a good "hit list" of procs that can be scripted out and removed.
I'll update this post when we get a good working version.
(Thanks to Hammer for his help)