Finderbase.com allows anyone who has lost or found an item to post it on Google Maps.
The map interface of Finderbase.com allows you to zoom into a region and view all found and lost items. The map uses categorised map markers. So, for example, if you know you lost your keys in a certain neighbourhood you can zoom into the area on the map select the 'keys' category and quickly see if anyone has found your lost possession.
Finderbase.com is in the open beta testing stage. Which means you can use the site but that there may be changes to the service as it develops.
Animal Finders in Oxford, UK provides a service for people to report lost and found animals in the Oxford area. These reports can be seen on a Google Map and are also distributed via email and SMS to key organisations plus members of the Local Pet Watch scheme in the Oxford area.