http://mapki.com/wiki/Google_Map_Parameters
Very handy page that contains a list of all the url parameters for Google Maps allowing the easy creation of custom maps without a google account. :-)
http://code.google.com/p/gmapcatcher/
An AWESOME piece of code that creates a python based gui google maps browser and auto-downloader for offline user. Really, really, really useful. :-)
http://www.mapstraction.com/
Mapstraction is a library that provides a common API for various javascript mapping APIs to enable switching from one to another as smoothly as possible.
http://weatherbonk.com/
Weather route planning, pretty awesome stuff... :-)
http://www.openstreetmap.org/
OpenStreetMap is a free editable map of the whole world. It's a wiki-like map which users can edit. You can upload GPS traces of areas and add street names, etc. Eat your heart out Google Maps.
http://bluweb.com/us/chouser/gmapez/
Want to put a Google map on your web page? With GMapEZ there's no JavaScript to write and nothing to download. You simply insert a div, add some xml, and bingo, the javascript does the rest.
http://www.phpinsider.com/php/code/GoogleMapAPI/
A PHP class that allows for the easy (and relatively painless) insertion of Google maps into web pages. Instantiate the class, call a few methods, bingo.
http://www.systemsevendesigns.com/phoogle
Google Maps API Class. Insert Google maps with simple PHP class method (function) calls.
