The UK-based think tank will publish a report on Tuesday that will underline the importance of "Pro-Ams" -- amateurs who pursue a hobby or pastime, in many cases an all-consuming passion, to a professional standard.
Demos says that these kind of people have traditionally made a contribution to society through involvement with bodies such as lifeboat rescue services or The Samaritans, but that they have now branched out into less typical areas.
"Pro-Am astronomers have made significant contributions to our knowledge of the universe. And Pro-Am software programmers who are part of the 'open source' movement are providing the only real challenge to Microsoft's dominance of the personal computing market," said the report.
The think tank pointed out that "derogatory names" such as nerds, geeks and anoraks have often been used to describe enthusiasts. It believes that Pro-ams is a more suitable label.
The launch earlier this month of Firefox, the open-source Web browser, illustrated the power of the open-source movement. While IT giants such as IBM, HP and Novell have all embraced the Linux operating system, Microsoft -- whose dominance of the desktop computer is threatened by it -- has responded with its "Get the Facts" campaign in an attempt to slow market adoption of open source.
Demos reported that Pro-Ams are more likely to be men than women, and tend to be well-educated people with annual household incomes over Ãƒ,Ã‚Â£30,000 (AU$72,700). Pro-Ams are evenly split between part-time and full-time workers, but people who don't work are far less likely to be Pro-Ams.
Other Pro-am activities identified include photographers, gardeners and alternative therapists.
Demos is interested in Pro-Ams because it believes they help to generate "social capital", which can lead to greater community spirit and less crime. Because the open-source community is spread around the world and generally operate over the Internet, their social contribution is made in a different way.
A Demos spokesman, pointing out the positive contribution made by the open-source community, said: "I think you could successfully argue that open-source enthusiasts are doing in the virtual space what lifeboat men are doing for seaside towns."
Demos argues that the government should take active steps to encourage and nurture Pro-ams. This could include days off work for employees to engage in activities and volunteering, or a national programme for 16- to 21-year-olds who want to spend a year on social Pro-Am activities.
However, the think tank is concerned that government intervention could actually hinder the open-source world, so it isn't recommending it.