The Montana GOP has created a blog for the upcoming session which they call the Rotunda Report. I have never really felt that writing letters or making phone calls have much of an effect on our elected leaders, but by publishing a blog and allowing comments (registration required, and the comments are moderated) you will be able to see that your comments made it, and you can also see the comments after yours.
This idea is truly revolutionary, and could probably only done in a state like Montana, where you have a better chance of actually knowing your representative. Well done to them. Now let's get the comments going on how they are doing.