We are thinking of creating some smart monkey tests. Basing this on @isTest Apex tests seems obvious, but we would need to record the random factors (a few random numbers) used in each test. It is my understanding that as database changes are rolled back and web service calls have to be mocked in tests, there is no way to add such information to the test output. So @isTest Apex tests is probably not the way to go.
Or am I missing something?