The free disability and life insurance through Great-West Life is by itself more than worth the membership. I have tried to obtain a disability policy and they just don't exist for 1st/2nd year dental students. Most only will sell disability policies to 4th year students and residents. I think I found one company willing to sell to a 3rd year student. And life insurance? Can't ever have enough.
Also, the ADA helps us and our profession in many ways, we have a strong lobby with them. Good to support the association that looks out for dentistry, which congress loves to overlook when they mess with healthcare laws.