Some schools may have graduate/professional sororities or fraternities. Of course these organization may be different then undergraduate greek life. However, they may give you an opportunity to make connections with people who have the same interests as you.
I started pharmacy school last year and joined a women's pharmacy fraternity, Kappa Epsilon. It was a great way to meet women further along and will provide me with great connections in the future. The funny thing is one of my KE sister is also a Phi Mu