Yahoo! has publicly launched two new (previously internal) libraries
calibre is a free and open source e-book library management application.
The Freesound Project is a collaborative database of Creative Commons licensed sounds. Freesound focusses only on sound, not songs
jQuery is a Javascript library that takes this motto to heart: Writing Javascript code should be fun. jQuery acheives this goal by taking common, repetitive, tasks, stripping out all the unnecessary markup, and leaving them short, smart and understandable
A Modern, Lightweight Open-Source JavaScript Library for Interactive Maps
OPDS is a lightweight open standard used to create catalogs that enable the aggregation, distribution, and discovery of books, journals, and other material by any user, from any source, in any digital format, and on any device.
OpenCV (Open Source Computer Vision) is a library of programming functions for real time computer vision.