It is not common see a Cisco crash: Software forced crash, Bus Error, Software watchdog timeout, and so on…
But if you would do it, there is a pretty trick : it’s the “test crash” command, an hidden IOS command. This can help you if you are lucky enough to have the real crash [...]

Surfing the web, I have found a document concerning the undocumented cisco commands.
The document is write by Lars Fenneberg (CCIE #7325) and it’s quite old (last revision in 2005).
Certainly this is not a complete list, but I suppose that could be funny to discover some new commands…
I have tried to found other document more exhaustive [...]