For a long time I've wished for a popular, centralized repository for packet captures. The closest I've known until recently is the Sample Captures page of the Wireshark wiki. While this is certainly a great resource, a wiki is not a suitable management system for such a collection.
Fortunately, I am not alone in wanting something better. Richard Bejtlich of TaoSecurity has been working on a better solution for the last few months which officially went public today: OpenPacket.org.
OpenPacket features a slick capture repository with an integrated rating system and discussion threads, community forum, and other resources. Members can post their own captures, and request captures of specific traffic from others. Being a brand new site, the repository is pretty barren, but I see this catching on quickly among network and security professionals. By all means, if you see interesting traffic, create a capture and share it with the world.