What's That I Hear (Phil Ochs)
Go Tell It On The Mountain (the Peter Paul and Mary, Let my people go, version)
Shirele Perele (Yiddish counterpart to Eliahu Hanavi, recorded by the Klezmatics, also by the Machaye Klezmer Band)
Dodi Li (taken from the Song of Songs, which is traditionally read on Passover)

My daughter and I did a set of Passover songs at the (Australian) National Folk Festival last year, our set list was those songs, together with Man Come Into Egypt (already mentioned earlier in this thread) and a few traditional seder songs.