One place I worked we also used a Wiki, but found that it wasn't updated often enough. Had to keep pushing people to use it.
Obviously we a crazy shared file system with matching shared email folders for project comms.
We also used an internal Instant Messaging system to avoid blanket emails around the office, but like Fog Creek I would probably now implement a private Twitter clone.
One thing we did is have a day each year where all the developers would meet up somewhere outside the office and present to each other on interesting things they had found/done. Sometimes stuff from projects, sometimes from personal work and sometimes from the day a month people were allowed to work on whatever the liked (like Google's 20% time).
