I am not sure how I would properly and clearly explain this question. What I am looking for in general is a tagcloud that is sensitive to context. So it will only list the tags that are relevant to the content that you are looking.
Let's say you have a repository of links all of which can be tagged freely. On the highest level (the entry archive page) you will have a tagcloud that shows all the tags that exists. Once you will click on one of those tags, it will list all the links that are tagged with that specific keyword. However, the tagcloud will now not show ALL tags, but just an aggregation of all tags within the context of the tag on which you have already filtered. Quite an abstract explanation. Let me try to give an example. Let's say you have 5 links, which are tagged comma separated:
Link1: tag1, tag3 Link2: tag1 Link3: tag2, tag5 Link4: tag3, tag5 Link5: tag4, tag5
So, on the highest level, you will have a tagcloud that shows all tags: tag1, tag2 ... tag5. Let's say you click on tag3. On the archive page of tag3, you will only see tags that are relevant to that tag, in this case: tag1, tag3, tag5 (see Link1 and Link4, both are tagged with tag3, but have tag4 and 5 additionally)
I hope I could make it a bit clear. Any clues on how to accomplish this with Drupal?