Patricia Barber has given her latest album (due in about five weeks from Premonition) the title Cafe Blue; now, two nights a week, she turns the Green Mill into just that. Instead of the big piano on the west-wall stage, she sits at the baby grand nestled in behind the bar, which allows her to create an intimate envelope within the cavernous saloon. And if anyone knows how to fill an intimate space, it's Patricia Barber. She knows that by always keeping something hidden she draws her audience in closer; she understands the dance. You hear it in her voice--cool and pale on the surface, yet unable to completely mask the passion beneath--and in the surprising audacity of her best arrangements, which suggest the strength of her imagination. In recent years the voice has turned so many heads--at such decidedly nonintimate events as the Chicago and North Sea jazz festivals--that people tend to lose sight of Barber's piano playing. It's their loss. Her piano lines have a radiant, backlit quality: they seem to shimmer, thanks to a combination of her discrete attack and the measured note choices that reflect her uncompromised intellectual integrity. Her new album features two songs for which Barber wrote the lyrics as well as the music, and these efforts--worldly excursions into territory normally reserved for pop and rock tunesmiths--could easily become standards for the fin de siecle 90s. As always, Barber works with her longtime bassist Michael Arnopol, a marvel of intonation and solo facility, whose dialogue with the pianist highlights the impact of the late pianist Bill Evans on her music. Sundays, 11 PM, and Mondays, 9 PM, Green Mill, 4802 N. Broadway; 878-5552.