Ranke, Gibbons and other historians of their era relied on their own personal libraries (See The Footnote: A Curious History). Sources for the history of Burma are hard to obtain, so people writing the history of Burma have to rely on their own personal libraries. How do they keep track of what is in these personal source libraries? Pieces of paper? Messy. An easily revisable database would be nicer and weigh a lot less.
Here is an example of how keyword tags could be used to organize historical source material. You have to use your imagination a little because this tag cloud is for the history of science.
In general any given historical source cuts across several different categories: 1. Geographical, 2. Temporal, 3. Economic, 4. Political, 5. Social. The source is about a geographical place located in a larger geographical region. The event the source documents took place on a specific date that was part of a series of events that took place over months or years and was part of a whole historical era. Tags and folksonomies can be used to described the source using these categories. Furthermore, each historian may have slightly different categories and categorizations. Attempts to be a dictator and determine the categories that everyone must categorize with...
Library Mashup CompetitionThere's a new library technology competition that's coming up soon. Organizing personal historical libraries might be a good opportunity to create a Mashup [web application hybrid] to compete in this year's Library Mashup Competition. The deadline for entries is in August.
Of course, one good organizing principle to connect the books to the authoring of history would be the Toulmin model of logical arguments (See "What is the Toulmin model").
Extreme Geekishness: Little warning boxes that appear everytime a historical interpretation was in danger of degenerating into one of the logical fallacies identified by David Hackett Fischer in Historians' Fallacies (many of these fallacies are online at fallacyfiles.org).