I spent a summer (Jun-Aug 1999) working at Monterey Design. I got a great experience with leading edge CAD tool development, and was one of the first to start work in what eventually became their Sonar tool, although I hope for their sake they destroyed all the code I had written.
In a previous life (Sep-Dec 1993, May-Aug 1994, May-Aug 1996), I worked for Teklogix Incorporated. They design and make wireless computer terminals and data entry devices. It was pretty cool there; they gave me tons of responsibility and treated me like a full-time employee there, even though I was just a co-op.
In another previous life (Jan 1995-Apr 1996), I worked with the Parallel and Distributed Systems Group at the University of Waterloo. There I worked on a digital cosimulation platform based on Xilinx 4010 FPGAs and Aptix FPICs. I worked for Professor Wayne Loucks during my stay at Waterloo. He's a terrific guy; always forgiving my goofups and overlooking my eccentricities.
In yet another life (May-Aug 1992, Jan-Apr 1993), I worked for Reuters (formerly I.P. Sharp). They taught me APL there, and I've never regretted it.
Even before that (1987-1991), I worked summers at Ironshore Management as a bookkeeper/accounting assistant. I really learned how to use spreadsheets there.
Finally, in prehistoric times (1985-1987), I worked for the North York Board of Education indirectly, as a free-lance programmer. I only got C$3.50 an hour, and the French-language software I wrote never sold, but at least it got me an interview with ABC Television.
I used to be an active memeber of the University of Waterloo Computer Science Club, and among other stuff maintained the CSC Programming Contest Archive. I haven't updated it in quite a while. There are many other, much better archives out there now (Google is your friend), so it's about time to retire mine.