Madness: ''Madness.'' (Geffen GHS 4003.) Why isn't this band more in the forefront of the music scene, and why hasn't it been? Since 1979 these loony characters have been producing truly great ska-rock-and-roll. What is ''ska,'' you ask? It is reggae-influenced rock combined with a sax and brass section. This hybrid results in the big-band sound of yesteryear and a more orchestrated sound than rock. Ska music facilitates social commentary, and every track of this album will provide the listener with an insight and a beat that will make the mind and the body move to its insistent rhythms. From the new hit single ''Our House,'' to an old version of ''Nightboat to Cairo,'' to ''Rise and Fall, '' these guys reveal through their music their motto: ''Love is the best.'' Their compassion for humanity enables them to point out human foibles in their lyrics, and to make these faults less heinous and terrifying by poking fun at them. After all, they lovingly pat us on the back with ''madness is all in the mind.''