Valve is offering a reward to one lucky member of the Half-Life primary server program. Here's the announcement sent along by Jenni (which I should have posted yesterday):

In an effort to thank those who joined Half-Life's Primary Server Program (PSP), Sierra Studios and Valve will be giving away a free trip to Valve to one lucky PSP member. To be selected, these members must be registered participants of the PSP and have their server up and running this Saturday. The 100 chosen at random will be sent a Team Fortress Classic T-shirt. Then next Saturday, April 17, Sierra Studios and Valve will check these servers again and select one of the hosts at random to come to Kirkland, WA and spend the day at Valve.

Those who are not currently enrolled but would like to participate must complete the short questionnaire and download the server software from CNET's Gamecenter.com.