I consolidated my federal student loans at 3.75% back in 2006. The amount of principal is about 50,000.
Is it possible to refinance the consolidated loan now, to take advantage of what I assume are lower rates? If so, how much would the refinance process cost, and what subsidy could I expect from doing so?
Thanks.

You are only eligible to consolidate once in your lifetime. That sounds like an exceptional rate to me.
I would check out They have a ton of fantastic info on how to refinance your loan for a lower rate, refinance laws and rules, and everything to do with refinancing a loan.
schools.medianewsonline.com – it provides some tips about applying to US federal and state grants for college students.