I grew up with most of these (and the Country Joe song Inge mentions). Here are a few more (a bit less well known) from the era:

Hedgehoppers Anonymous, "It's Good News Week"

Eric Burdon and the Animals, "Sky Pilot"

The Byrds, "Draft Morning"

The Kinks, "Some Mother's Son"

Jefferson Airplane, "We Can Be Together"

Pearls Before Swine, "Balaklava" (the entire album--imo, the most profound anti-war statement of all time, but there are no protest songs on it)