Here is the announcement we received calling for entries in the third annual Half-Life mod (or, as they put it MOD) expo:

The Third Annual Half-Life MOD Expo, showcasing the latest Half-Life community developed MODs, will take place Thursday, September 27, 2001 in San Francisco. Sierra and Valve invite MOD makers to submit their handiwork to modexpo@valvesoftware.com for consideration. MOD makers have until Wednesday, September 5th to send in details about their MOD, AVI's and/or screenshots and contact information, including Web site. More information on this year's Expo will be released closer to the event.