Can you recommend a company that consolidates both private & federal student loans in repayment?

I have quite a few student loans, both federal & private that are in repayment. I feel like I am sending out a million payments to a million different loan companies every month. Problem is the total combined amount of all the loans I own from college amount to a great deal, and I am having trouble consolidating them with one company for ONE easy payment. Another thing I like about having one payment is that I can monitor interest rates, and make sure some of the principal is being paid. Can you recommend a company/bank that you've used in the past with great results?