It's traditional (and in a way almost expected) for first year law students to participate in a student organization of some kind. After looking at all of them, I'm signing up for two:
Immigrant Families Advocacy Project. The U.S. Government offers a special path to residency for domestic violence victims and their families. This student organization helps clients through the process. It's unusual in that: (1) there aren't that many other ways for 1L students to gain direct legal experience, (2) you work with a practicing attorney in a small group, and (3) the training provides extensive and useful background on immigration law just in general.
Becoming a legal observer through the UW student chapter of the National Lawyers Guild. After a brief training in the relevant areas of law, they send you out to large outdoor protests (for example the upcoming one on October 11) in case problems arise. Personally, although I'm still not convinced protests are actually that effective at changing hearts and minds, there's no denying that in contrast to all the other student organization activities this one will at least get me out in the open air :)