One of the best of all time #1 (or close enough) hits on a live album was 'Styx Live'. Like 20 hits, all performed flawlessly live, and mixed correctly. Go buy it at your local Dollar Store for 5$ (they sell BMG CDs there now).
Also, anything that 'The Kinks' perform live is incredible. Especially 'Alcohol', but that's very hard to find...