Suggestions for volunteer work

Hi. I’m a fourth year undergraduate geography student, and I’m planning on an urban studies concentration within my degree. I’m also considering applying for graduate school after I’m done with my undergraduate degree to obtain a master’s in degree in city/regional/urban planning.

I was wondering if anyone could offer any advice for relevant volunteer work that could be done during the summer or while I’m still in school. I need to consider letter of recommendation from non academic sources, and it would get great to get some measure of planning experience outside of the classroom. Is there anything in particular that I should check into within my locality? I’m in San Francisco if anyone knows anything specific I could do around here.

Thanks in advance!