This won't be applicable to all, but for those who ride in cooler climates and/or have poor circulation here's a neat way to insulate your levers.
I like to leave two fingers on my brake and clutch lever. This means that those four fingers don't get heated by the heated grip wraps. I considered two basic solutions. The warmest would be to build electric lever warmers but this would take more time and work. The easier solution, which I chose to try, was to insulate the levers. Someone on sport-touring.net suggested using fabric hockey tape. I used three layers and it worked so well on the WRX in the first few days of spring commuting that I have now wrapped the levers on my Ducati touring bike and that's working well too.
I won't rule out making lever heaters one day, but this is pretty cheap and easy. Hopefully someone can benefit from the information passed on.