LBNL/ICSI Enterprise Tracing Project has 11gb of anonymized packet traces that span more than 100 hours of activity from a total of several thousand internal hosts.

"While wide-area Internet traffic has been heavily studied for many years, the characteristics of traffic inside Internet enterprises remain almost wholly unexplored. Nearly all of the studies of enterprise traffic available in the literature are well over a decade old and focus on individual LANs rather than whole sites. A goal of this project is to characterize internal enterprise traffic recorded at a medium-sized site, and to determine ways in which modern enterprise traffic is similar to wide-area Internet traffic, and ways in which it is quite different."