I've recently looked for a voltage comparator + op amp in the same package, but it seems that the LM392 is unique (does anyone know other similar, better spec ICs?). I bought a few LM392s and they were not that cheap. I used them in very low frequency applications and they worked fine.
As usual one should consider/evaluate the requirements of the particular application he is designing (frequency response, slew rate, input currents, output voltage swing, etc). National's app note 74 explains how to configure an unused comparator of an LM339 as an operational amplifier, suitable for low frequency applications (for example it can provide a DC reference voltage for the other three comparators in the same package).