There are many extracurricular clubs and organizations on and off campus that may be of interest to architecture students. You may find a complete list of groups affiliated with Barnard College here and student organizations affiliated with Columbia College here.
Additionally, here are a few specific organizations that may be of interest to architecture students:
The Barnard + Columbia Architecture Society
Barnard/Columbia Design for America
Architexx
Society of Women Engineers
The American Institute of Architecture Students
The Architectural League Student Program