Gray code
M-sequence (uPen)
Bloom filters
Rainbow tables/chains
Skip lists
Quake3 networking model
http://bookofhook.com/Article/GameDevelopment/TheQuake3NetworkingModel.html
Join claculus
Polyphonic C#
http://research.microsoft.com/%7Enick/polyphony/index.htm
Pi calculus
http://www.ifi.uio.no/dbsem/foils2003vaar/introPiCalculus.pdf
Capabilities
YURL/Web-calculus?