For icy and/or mixed conditions (hard packed snow, cleared ground, icy, & slush) I wear Get-A-Grips Ice Joggers.  I think Yak Trax are great for snow, but they don't work well on ice or when the pavement is clear.  You can run on asphalt or concrete in Ice Joggers; it's annoying, but you don't really slow down and you have them when you hit an icy spot.

I buy them from QVC, but if you Google the term, lots of places sell these. BTW, I use these on my everyday shoes/boots, too.

Mary

I had used the screw shoe option (see post by trifecta082) for several previous seasons (usually have to deal with ice 4+months months per year in NH) and agree that they are way better than the Yak Trax and Stabilicers.  However, last year I discovered a much better option called Icespike ( http://www.icespike.net/ ).  Similar concept as the screw shoes but one set lasted the whole winter (30-40 miles/wk, clydesdale runner).  With the screw shoes (sheet metal screws), I was changing them weekly.  Great traction, comfortable, super light, long lasting (and less expensive than Yak's or Stabilicers).