Applications are now open for Google's [Northern] Summer of Code. If you are currently a student with aspirations to becoming a master programmer, this is a fantastic opportunity to contribute to an established free software project with guidance from some of the top people in free software. There are 135 mentor organisations participating this year, including projects like Debian, GNOME, KDE, Mozilla, Samba, and on and on. So no matter where your interests lie, you will probably find a project you'll want to work on.
Last year the SoC contributions to Drupal, the software my day job is built around, really helped push development of some major features. And many of the mentors from Drupal in 2006 were themselves student participants in 2005, so this is really a serious stepping stone to getting a career in free software development off the ground.
Oh, and Google pays you for your work! Beats stacking shelves in the supermarket to make ends meet. There are a lot of things you can criticise Google for, but on the strength of this program alone, they can justifiably claim to be not yet wholly evil.