JAVIER is a JAvascript Voicexml InterpretER, designed (but not restricted) to run inside a web browser, its main engine has less than 1000 lines of code. It's maybe, the tiniest but (almost) FULL VoiceXML implementation.
P3nfs makes the drives of Symbian/Epoc devices available under Unix. Its name comes from the Psion Series 3a, which was the first supported device. Current devices include Nokia and Sony ericsson phones.
Cryptofon - a safe phone with integrated encryption.
The Cryptofon is designed to enable safe and secure communication trough a regular PSTN line. It supports narrowband connections (~2400 bit/s and lower).