This question is similar to this one: What unique features has Ubuntu brought to the Linux community? but in this case it is directed towards what has Ubuntu contributed to the official Linux Kernel.
Many times I have heared about Intel contributing patches to the Linux Kernel like the RC6 latest patches and many more related to recent support for Sandy/Ivy Bridge. In another group, Android did an upstream patch and a lot of ARM patches have also come to the Linux Kernel.
I have seeing a small percent of companies and groups that have contributed to the Linux Kernel (http://kernel.org) but what I want to know is, since the beginning of Ubuntu till now, what has Ubuntu contributed to the Linux Kernel in regards to any aspect of the kernel.