linux-libre - the free kernel
Some distributions remove the proprietary code.
For those wishing to roll their own kernel (The Linode library has great tutorials on this), without the non-free code, the Free Software Foundation Latin America (FSFLA) release a version of the Kernel that is 100% free.
I have compiled the most recent version which I am currently running on my Linode now
OMG no wonder the IRS is monitoring everyone's online transactions.