for allopathic schools this is the honors society
for DO schools the AOA:
The AOA is a member association representing more than 56,000 osteopathic physicians (D.O.s). The AOA serves as the primary certifying body for D.O.s, and is the accrediting agency for all osteopathic medical colleges and health care facilities.
The AOA's mission is to advance the philosophy and practice of osteopathic medicine by promoting excellence in education, research, and the delivery of quality, cost-effective healthcare within a distinct, unified profession.
in a number of threads especially the residency forums they talk about being AOA (honors society) which helps in making your residency app stand out. This is the allopathic honors society they are talking about though.