I work on the Squid Web Proxy/Cache software; primarily in the areas of network performance and object storage. My Squid-related scratch site can be found here.
My current work is on improving the file store code and interfaces inside Squid. I've broken it up into a few stages:
The COSS code already outperforms the UFS/AUFS/DISKD code in Squid; I'll put in more effort into comparitive figures after my Semester 1 exams. It does have some noticeable problems with disk IO and scales rather poorly; I have ideas on how to fix this but I'll wait until the code has been tested and I have feedback from others.
Random Update: Steven Wilton at Eftel took COSS and fixed the couple of disk IO performance issues with some clever ideas. COSS now performs quite well!