When users delete their own accounts (with the core function), I don't want the username to be replaced by anonymous, but with a hash string, for example anonymous-dhjf4ued.
I tried doing it with the Rules module, and I looked for modules that could do it, but I couldn't figure it out.
The reason this would be useful is because I have sites with a forum and threads are much more readable if you can still identify which users are the same (who responds to who) if there are two cancelled user accounts in a single thread.