Also driver staging is always looking for more contributors and you
can get a good feel for what is going on on the mailing list:
devel.linuxdriverproject.org
(devel at linuxdriverproject.org)

Read the TODO lists for various drivers in the in the kernel tree in
drivers/staging/ and pick something you would like to do. Don't forget
to read the relevant files in Documentation/ for preparing/submitting
patches, etc, and make sure you cc the relevant maintainers when
sending patches to their drivers to the list.

If you're not doing it already by far the easiest way is to use git to
manage your kernels, you will be expected to test your patches against
linux-next or some branch specified by a particular maintainer which
you can remote track (I think it's staging-next on Greg's tree for
staging, but it wouldn't hurt to ask the maintainer once you have the
patch ready).

Cheers
Julie

Oh, and another suggestion - find out what hardware you have and find
out what corresponding drivers cater for it in the kernel. You can
then join the appropriate mailing lists (filtering on their throughput
if it's large) in order to catch any new patches or bugs that appear
there for your hardware. You can then work on testing the
patches/helping fix the bugs, which is especially helpful when done by
people who have the actual hardware to test with. If it's new stuff in
staging, I think the staging people would particularly appreciate
this.

Cheers
Julie