Well, Sigma Gamma Rho is a service sorority founded for some of the same reasons Senusret mentioned: social action, networking, academic advancement and sisterhood.
I'm interested in SAI but there is no chapter nearby and I can't charter a chapter at my school because we have no music department.

I played the flute, violin and piano.
Years ago , when I was at Grambling State U, I had transferred in and did not have the prerequisite number of units or class standing to join any greek lettered org

There were no NPC's, only Honors and NPHC's, and music orgs. There were also the ROTC orgs Perishing Rifles, and I can’t remember the name of the other ones something Angles. Anywho, I'm happy where I am but if the opportunity ever arises for membership into SAI, I'll jump on that bandwagon!
ETA: One of my best friends is a PMA (Phi Mu Alpha Sinfonia)I always though it would be cool if we were both in musical orgs