Space Resources Roundtable, and In-Situ Resources Utilization (ISRU)
A leading non-profit group which emerged around the turn of the century is the Space Resources Roundtable, which uses the acronym ISRU for In-Situ Resources Utilization. It is headquartered at the Colorado School of Mines.
The Space Resources Roundtable actually started informally, including meeting as an adjunct side program at conferences in the 1990s. In 1999, the Space Resources Roundtable held its own conference, which thereafter became an annual event. In 2001, the Space Resources Roundtable formally organized as a not-for-profit organization, and received tax deductible 501c(3) status in 2003.
The Space Resources Roundtable is composed largely of academic, former NASA, and private sector industrial participants, and its main activity is the conferences, and correspondences in between.
The Space Resources Roundtable continued holding its own annual conferences thru 2011 though I had not seen any plans yet for one in 2012, as of April 2012. The year 2009 was the only one skipped. From 1999 thru 2007, the conferences were held at the Colorado School of Mines. In 2008, they were held at Cape Canaveral, Florida (near a NASA launch site), and in 2010-2011 the conferences became jointly sponsored by the Planetary & Terrestrial Mining Sciences Symposium, in Ottawa, Ontario, Canada.
Notably, the Space Studies Institute (SSI), discussed in another section of this website, had previously been hosting the premier space resources conference bi-annually in Princeton, but had been waning in activity since the death of its leader, Dr. Gerard K. O'Neill, in 1992, despite the organization's Boards and staff continuing on. The Space Resources Roundtable had been picking up a lot of the slack by simple default at the time. For example, the SSI bi-annual Princeton conferences stopped for awhile after #13 in 2001, and it was 2010 before SSI Princeton conference #14 came around. Many of the same people participate in both, and it's generally the same community.
You can read Space Resources Roundtable conference proceedings on their website, isruinfo.com