Alright, San Francisco, it's time to buck it up and do some volunteer work. A Chronicle item tips us off that the Department of Public Works needs a hand with Arbor Day activities this Saturday, 9:00 a.m. to noon. It's a tree-planting and community clean-up in District Five, which includes the Haight-Ashbury, Hayes Valley, the Western Addition, Alamo Square, and the Inner Sunset. And if doing something nice isn't enough inspiration for you, there's free lunch, too. Besides, what else could you possibly have planned for a Saturday morning? Register online.