This is a tip specifically for Mac users, but it's got interesting implications beyond the Mac universe.
"This AppleScript will add a 'Google Map Of' option to the Address contextual menu in the Address Book application. It will open Firefox and map out the address on the new maps.google.com mapping service. Note that Firefox *must* be installed for this to work." From MacOSXHints.com
Linking personal stuff to web searching. Hmmm. Lots of issues -- privacy, convenience. Implications for librarians? Linking favorite books to the catalog? Radio streaming playlist to amazon.com to buy CDs?