Threads considered harmfull - a fairly controversial discussion on kuro5hin.org about the dangers of thread programming. In my opinion, a whole range of problems are addressed that arise with threads in programs, and that often the same problems can be solved more simply and efficiently in other ways.
I discovered an example myself not long ago, the Medusa Webserver. It works completely without threading and processes, instead using input dispatching. In doing so, it even implements multiple virtually parallel running servers in a simple and efficient event loop. Medusa is also the basis for Zope. There, however, multiple processes are pre-started and centrally managed. In the Python Community Server, on the other hand, Medusa is contained in its pure form.