OpenUsability's Season of Usability is a series of sponsored student projects to encourage students of usability, user-interface design, and interaction design to get involved with Free/Libre/Open Source Software (FLOSS) projects. Students experience the interdisciplinary and collaborative development of user interface solutions in international software projects while getting into FLOSS development.
If you are a student of design, usability, human factors, or other HCI-related field and you are interested in working on an open source project, you could work with an experienced usability mentor on a fun and interesting design project (including the University of Toronto's OLM). As a bonus for working 10-15 hours a week between June 1 and August 31, there is a $1000 USD internship stipend at the end of the project. For more details, see the Season of Usability site.