Summarizing where the presidential candidates stand on the issues

Although I am an Obama supporter and have some sense of where he and his opponents stand on various issues, I haven't worked to make my understanding systematic. In addition to reading widely and compiling my findings, I figure that I could get a jumpstart by first studying the Wikipedia article Comparison of United States presidential candidates, 2008. One thing that you immediately learn at a glance from the article is that there are people other than McCain and Obama running for President. I like most people tend to ignore those minor candidates because they have very little practical chance of winning. However, their advocacy for other positions serve to critique and illuminate the mainline candidates' positions. It's all too easy to confine ourselves unnecessarily to the relatively narrow spectrum of thinking represented by Democrats and Republicans.