SPIN - Dynamically extensible, Exokernel-based, provides many core services: scheduler, kernel threads, domains, event dispatcher, security mechanisms, primitive VM operations. Blurs distinction between kernels and applications, which traditionally live in user- - http://www.cs.washington.edu/research/projects/spin/www/
Novel OS Work - By Christopher Browne. Very brief, clear descriptions and some critiquing of many OSs, mostly research types, with many links. Puts much current activity in larger context. - http://cbbrowne.com/info/osnovel.html
FunOS - Proposal for LISP oriented OS based on Assembly, Caml, FunScheme, a Scheme variant of LISP language. - http://www.sarg.ryerson.ca/~cmwilson/code/funos/funos.html