http://www.serenadawn.com/rpgdatabase.html2 systems of particular note here are the Aliens Fuzion and the Ghost in the Shell D20 Modern
I've had a look through the Aliens one and it seems to have a huge amount of depth
Wierd...I'm surprised they didn't go for Gurps when they did GITS - there's already plenty of rules on cybernetics etc... from Transhuman Space.