Debugging Zope via the command line. Also, boa constrictor is a crossplatform python IDE with zope support (More about boa-constrictor).
Shane Hathaway (a blogger ) and author of several zope tools including zope, DCWorkflow and others, has a product, Verbose Security, for use with BoaConstructor. Shane has been fiddling around with Zope3 and seems to have good things to say about it.
While I’m at it, here’s some articles about ZopeUnitTesting and a ZUT Testing. (There is some plone information about it as well).