Their website is weareamericaalliance.org, which redirects to cccaction.org/cccaction/waaa_home_page.html
A partial list of their members is here.
Immigrant Supporters To Counter Bush Speech says that the Central American Resource Center (CARECEN) as well as unnamed "Catholic churches" are also members of WAAA. That article also compares WAAA to more militant groups such as the March 25 Coalition.
Forum to address impound law (tangential link to Mexican government)