I think a really good trick to use if you are using less than great speakers, is to listen through an EQ (whether in your DAW or mp3 player like winamp or whatever) and set the EQ so that your reference cd's sound their absolute best to you on that pair of speakers. Use reference cd's you know you already like and you know are very good. Set the EQ so that it is balanced for a bunch of different reference cd's.... as in, an EQ that makes a wide variety of music sound it's best through your speakers. then use the same EQ on the master while mixing and try to get as close to possible to your reference cds (which you already know are great, so you don't need to double guess yourself). after you do this a few times, you won't need to keep checking the reference cds (if you don't want to), and the balance should be just right. and, of course, remember to turn the EQ off before rendering your master mix. it's only there for your monitoring purposes. you don't want to leave it on when you mixdown.
obviously it's not ideal, but I think someone with a really good ear for how the music should sound and who is capable of mimicing good reference cds can definitely do some awesome stuff mixing this way. if anything, mimicing good reference cds a few times is just helping you learn how it should sound, and after a little while you won't need to. if you really think about it, if so many people mix on yamaha NS10s, then there's no reason this can't work also.