I use an
IBM model M with a PS2-to-USB converter :o)
I use a Unicomp Customizer. It's
black/silver and has native USB. It
also uses the famous IBM/Lexmark buckling-spring mechanism.
BTW an old dream of mine is finding an IBM "M" keyboard with the
trackpoint (know as "clitoris" in Brazil...go figure! :oD). I'd love to buy
one, any info? :oD