I am a user of Facebook, but not as frequent as my friends. But I do find that the open source tools provided or contributed by Facebook interesting.
Facebook has indeed provided some very good open source tools
- Facebook Open Platform is a infrastructure that runs Facebook Platform
- Thrift is a framework for scalable cross language services development
- MemcacheD – Facebook contributed modifications to the project
- Cassandra is a distributed storage system for managing structured data
- phpsh – an open source interactive shell for php
- Facebook Firefox Toolbar
- Facebook Exporter for iPhoto
- flvtool++ – a tool for hinting and manipulating the metadata of FLV files.
- PHPEmbed – simplified API on top of the PHP SAPI
- Public Patches Library – collection of patches that enhance open source projects like PHP, Apache, etc
- Facebook Mirror – public mirror for projects such as Apache, Linux, Mozilla…