I use SONY earbuds. Just kidding. I'm A/B'ing mixes between SONY MDR-7506's and Beyer Dynamic DT 770 Pros (I primarily use the Beyer's). I then periodically play back my current mix via the M-Audios, and when I think I'm complete I'll burn it to CDR and playback on the stereo, and a discman and/or iPod to make sure things sound like where I want them to be.
I don't know why people diss the M-Audio monitors. I find the Mackies disturbingly tight. At least the short time I had with a pair - they were incredibly fatiguing to me. Not saying I could do better on monitors, I know I could, but not sure I like the HR824s. Haven't heard much good on the Adam A7s either. The M-Audios have, what I call, a slightly sloppy bass end, but not that bad at all, plus I would consider many consumer level speakers to be more bass heavy and I find I compensate my low end rather well because of this. Plus, they sound kick-ass when I play other music through them.
If I ran a studio and did this full time it would be a much different story... for what it's worth, and to make me seem cooler, I had planned on abandoning any further synth purchases with plans of really spending a nice chunk of money of a few different studio pieces, but joblessness and hearing loss threw that idea down the hatch. I am planning to rely on 3rd party people for mastering (or otherwise help me fine tune the final mix) of my tracks from now on - although I do wish I could afford to submit individual stems, but that just starts to get too pricey. Sigh.