alt Hacker NewsHighly recommend writing a BitTorrent client. The spec is easy to grok, it has a bunch of fun subproblems that you can go as deep or as shallow as you want into, and it's super rewarding being able to download something like the Debian kernel after all of your hard work. Magnet links and seeding are two fun things to tackle post basic implementation. It also got me really interested in peer to peer systems and DHTs like Chord!
In college one of our end of semester projects was to make a “peer to peer” client. Not specifically BitTorrent. It was so much fun! Coming up with the ways of handshaking, chunk sizes, etc. It was so cool to see it actually work as a new student.