Ed Sanders, second from right, above — who co-founded the Fugs with fellow poet Tuli Kupferberg in 1964 — performed the band’s songs at Kupferberg’s memorial at St. Mark’s Church in the Bowery Saturday. There was no religious element to the service. Kupferberg was buried in Brooklyn’s Greenwood Cemetery on Monday. At right, Kupferberg in his Soho apartment in 2007. Street memorial for activist: Similar to white “ghost bike” memorials left where cars have killed cyclists, a “ghost crutches” memorial recently appeared on a parking-sign pole on Essex St. between Stanton and Houston Sts. Harry Wieder, a disabled Community Board 3 member who used arm crutches, was killed by a taxi there while crossing the street after C.B. 3’s April meeting.