A real Web 2.0 application needs a serious mashup(web_application_hybrid). At least the folks at ResearcherID thought so. You might remember that ResearcherID creates a unique author ID for each interested scientist and was launched by Thomson Scientific (recently renamed to Thomson Reuters) earlier this year.
The new ResearcherID features include a mashup with Yahoo Maps that shows the location of your collaborators. Here are some examples from fellow Nature Networkers:
Wentworthville, Australia is the furthest I can go to find a paper coauthor.
Now the really interesting question would be: when do we see mashups with Nature Networkers? For a start we have the Nature Network London Flickr Mashup created by Matt.