The sigrok project aims at creating a portable, cross-platform, Free/Libre/Open-Source signal analysis software suite that supports various device types (e.g. logic analyzers, oscilloscopes, and many more).
WeeWX is a free, open source, software program written in Python, which interacts with your weather station to produce graphs, reports, and HTML pages. It can optionally publish to weather sites or web servers.
wview is a collection of unix daemons which interface with supported weather stations to retrieve, archive in SQLite, send alerts, report (to CWOP, Wunderground, WeatherForYou, Awekas), and generate HTML and RSS from the weather data.
Able Wits RS232 Emulator for sending WITS (Wellsite Information Transfer System) packets over serial port and TCP/IP.
United Kingdom