Software Freedom Day
From Wikipedia: Software Freedom Day
Software Freedom Day (SFD) is an annual worldwide celebration of Free Software. SFD is a public education effort with the aim of increasing awareness of Free Software and its virtues, and encouraging its use. Software Freedom Day was established in 2004 and was first observed on 28 August of that year. About 12 teams participated in the first Software Freedom Day. Since that time it has grown in popularity and while organisers anticipated more than 1,000 teams in 2010 the event has stalled at around 400+ locations over the past two years, representing a 30% decrease over 2009.