On May 9, 2001 1632 UTC I was able to talk to the crew of the ISS. I spoke to Mission Specialist Susan Helms, who is also a ham. Yes, it was VERY cool! At the time I was on my lunch hour, and was operating from my pickup truck, running 50 watts into the antenna shown on my home page. Normally only a couple of watts ERP is needed for space communications. But in this case, everyone wants to talk to the Space Station, so that is why I was "barely readable".
Below is a MP3 file of Susan acknowledging my callsign.