A list of open-source HTTP proxies written in python - many of them are still active, and potentially quite interesting for mobile use (especially those based on asyncore, due to the low resource usage)
Archive 21. January 2006
runit - a UNIX init scheme with service supervision - alternative to sysv-init with more possibilities and integrated features like supervise (from the daemontools).
WebCleaner - a filtering HTTP proxy - absolute high-tech, that part. Asyncore, so low resources, built-in JavaScript interpreter against obfuscation and a bunch of other features. Sounds very good on paper.