See the second answer here
http://stackoverflow.com/questions/13480462/erlang-can-i-get-a-list-of-all-currently-registered-atoms
It's a neat trick which could of course break an any point, but I could imagine something which captured the current count, paused, then captured again helping out in the cases where you are programmatically creating atoms (or something is), and you don't know what.

Assumably, the system might first crash with full atom tables or something like that, they you start up with recon and see what's growing the table? At least that's a use-case I could imagine.

What do you think?