One of my favourite books, Cryptonomicon by Neal Stevenson, contains frequent references to a specialist mailing list for crypto geeks. The problem is that, in the real world, any mailing list offering high-level cryptographic discussion quickly gets colonised by opinionated numpties. So, in true Darwinian form, they're quite hard to locate.
I think I've just stumbled across one here. This is great for me, because I've wanted to develop a more advanced knowledge of cryptoanalysis for some time. Probably not so good for the list that it's been discovered by the outside world.
Once my forthcoming actuarial exams are over, I'll have to have a browse through the archives (in between learning Bengali and ancient Assyrian and brushing up on my computational biology). I'll let you know if I discover anything particularly interesting.