One example you may have seen was the original apexblogs.info - this was a detail view IR showing aggregated posts of APEX bloggers.
It's now hosted at odtug.com/apex and this appears to use an alternative method - Named Column report template. I now feel this is probably more superior and deserves it's own post.
I also thought the APEX 4.2 builder application search was another candidate, but looking under the hood it doesn't appear so. If you were just observing as a user you'd say ifthis wasn't implemented with an interactive report detail view, it certainly could have been.
Trouble is these Detail Views aren't shown by default. Good thing is this has a simple solution, though the mechanism may change in APEX5 or other versions.
All you need is to add this when the page loads, either under page attributes or as a dynamic action.
gReport.data.view('DETAIL');'ICON' is the other accepted actual parameter.
Suggested linksOracle Docs - Enabling detail view
Understanding detail view [video]
Oracle APEX Techniques - video course that includes this clip