Google Trends is my new favorite tool for tracking the popularity of political party primary candidates. Here is a comparison of five of bigger Democratic candidate (including Bill Richardson, currently my personal favorite). Here is the same for the Republican party. It is difficult to say exactly what high or low search volume indicates about the popularity or name recognition of a candidate. I would think that search volume would be indicative of some combination of the current popularity of a candidate and rate of new interest in the candidate, while news reference volume is indicative of media support for a candidate.
If I could figure out a way to pull data off of Google Trends, I would compare these results with polls. Also, the data seems only to go up to February.