Back when she was working at Second City, before she moved to LA to launch a TV career, Dear John's Isabella Hofmann could be frequently found in nightclubs hereabouts vocalizing with singer-songwriter Tony Zito, whose long track record ranges from the 1970 road show of Hair and the pop recording duo Frannie and Zoey to writing a string of scores for plays and musicals at the Body Politic, Goodman, and other local theaters. Hofmann is one of several entertainers donating their talents to this benefit concert of works by Zito, who has been prevented by illness from working much of the past year. The program is organized by June Pyskacek, producer of the original Grease and Zito's coauthor on The Influence Show, a long-running Body Politic hit in the 1970s. Joining Hofmann in selections from that and other Zito musicals are Jill Kotler, Nell Wade, Bob Neches, Kathleen Hall, Mark Rafael Truitt, and Calvin "Champagne" Powell; pianist-about-town Bob Moreen is musical director. Sunday, 6-9 PM, Yvette Wintergarden, 311 S. Wacker; 408-1242.