Sharing markers on Google Maps
 

It's a fairly simple application, originally made for one of my professors (hey, it was either that or spend several weeks rectifying vector maps by hand...).

Anyhow, you're welcome to a copy. Let me know if you find it of any use. :-)

Get the archive here: http://code.google.com/p/gpin/downloads/list
Or check it out of SVN repository: http://gpin.googlecode.com/svn/trunk/