Here are some fascinating resources related to the history of Princeton Theological Seminary.
In the Special Collections dept of PTS library you can choose to browse from this list of stuff. And just look at this list of personal papers and archives. Talk about being spoiled for choice...
In the digital collection, I tried to read Hodge's manuscript of his trip to Europe, but his hand writing was too bad. Perhaps the real thing will be easier to scan!
And, interest in Benjamin Warfield's legacy continues to grow on the web. Here is one site with resources, including this link to a dissertation on Warfield's method that puts my own work in proper perspective. I have considered doing more work on Warfield over the next year or so, but I'm not sure where to go with it. Riddlebarger's essay is pretty good, but, like my own dissertation, it is basically a historical survey of aspects of Warfield's work.
I would love to be able to assess, theologically, Warfield's thought. It looks like his use of Scottish common sense philosophy is well acknowledged. However, his use of higher critical approaches to the Bible, his textual criticism, and his exegetical method still require anaylsis because they were far from being 'fundamentalist' even if they were still essentially conservative. In fact, despite Riddlebarger's claims that Warfield was not solely responsible for introducing higher critical methods to the Princeton tradition, I still think that, in conjunction with Warfield's doctrine of scripture, this is his main influence on evangelical theological method - the combination (the tension?) of a high view scripture with historical critical methods of reading (or defining!) that scripture.