I have just done a little experiment with the existing application. I have in the past talked about Citations and problems finding previous articles that I have written so that I can cross reference what I have been talking about. I have added in some functionality that will search kinlan.co.uk, to find in articles that are related by keywords that have been selected by the tagger.
All this is using the Yahoo API
and it works pretty well. For each tag that the I select from the article that is inputted in to the Ajax tagger, a link is shown for each of the posts that contain that key.
Give it a go if you want: http://www.kinlan.co.uk/AjaxExperiments/AjaxTag
and use this entry as an example input.
This is just a test at the moment, but some other more important aggregation features will be in the next version of the application.