At Lotusphere I ran into Li-Te Cheng who gave me a cool demo of some tagging abilities in Eclipse out there. There are currently two projects out there it seems that deal with tagging in Eclipse: Eclipse Resource Tagger and TagSEA.
TagSEA is more advanced in my opinion, but after thinking a bit about this topic, wouldn’t it be cool to tag things in your code and be able to share them with co-workers (or other people)? I could imagine tagging common code (maybe like saving an EMF resource) so it could easily be found again by anyone. This begs the questions whether those crazy Mylar guys would be interested in this type of functionality.
In the end, I think a del.icio.us type thing for Eclipse or source code would benefit the community.