There have been two conferences, and two proceedings volumes, on this topic.
In 2006, with funding from the National Security Agency (NSA), the AMS organized the "Promoting Undergraduate Research in Mathematics" (PURM) conference, which took place on September 28-30, 2006 at The Westin O'Hare Hotel in Rosemont, Illinois. PURM continued the work of the 1999 conference (see below) by bringing together a diverse group of people who are actively involving undergraduates in research programs of all types, in order that they might share their experiences and explore ways of creating more such opportunities, with the goal of bringing the most talented students into research level mathematics.
The proceedings volume for the PURM conference was published in June, 2007 and is available as a PDF document: Proceedings of the Conference on Promoting Undergraduate Research in Mathematics. Pending availability, a free printed copy can be requested by sending name and complete college/university mailing address to the AMS (see link, below).
In 1999, the AMS brought together mathematicians from across the country who have been involved in summer mathematics programs for undergraduates. The purpose of the conference was to exchange ideas, discuss issues of common concern, establish contacts, and gather information that would be of use to those in the mathematical community who are interested in establishing summer mathematics programs for undergraduates. The workshop was held September 30 - October 2, 1999 at Crystal City, Arlington, Virginia, with support from the National Security Agency. The proceedings volume for the 1999 conference was published in June 2000 and is available as a PDF document: Proceedings of the Conference on Summer Undergraduate Mathematics Research Programs.
A List of Summer REU Programs is also maintained on the AMS website.
Contact the AMS with questions submit an inquiry.