AshDigg and I have been wanting such a feature for a long time. The idea is to help predict stories that users might like based on their voting habbits, much like how Amazon predicts products that you might like based on what you have shopped for in the past. This method of prediction is called collaborative filtering. It works by comparing your voting habits with other users who have voted for the same stories. It then looks at what the other people who share similar interests are in to and suggest stories based on their habbits. There is already a collaborative filtering engine out there called
Vogoo that is designed to be used in such a way, but we still need to built it into Pligg. This feature is definitely something that we hope to integrate soon.
If you want a much simpler solution for your question you could probably whip up a script that searches for articles with shared tags and outputs the titles/urls. Not my area of expertise, but it shouldn't be too difficult to find someone to whip it up for a few bucks.