Let me briefly sing the praises of the open source MapServer project. If you’re interesting working with web-based maps, you should give it a look: it’s powerful, well-documented, well-supported and let’s you create very powerful mapping applications.
We’ve used MapServer to built the YankeeMagazine.com Foliage Map, and the Explore PEI tool. I’ve spent the last week building an intranet mapping application for Elections PEI and at every corner I’ve been heartened to find the sort of “hey, they already thought of that” goodness that typifies mature open source efforts.
Having spent many years struggling with closed source, proprietary web-based mapping products, I can’t tell you how great it is to have the hood open and my hands on the engine.
There’s a Canadian angle, by the way: DM Solutions Group is an Ottawa-based company that’s contributed tremendously to MapServer, including maintaining the PHP MapScript module and the ROSA Java applet that is a marvel of functionality and simplicity. Kudos to them for a job well done, and for contributing to the open source ecosystem.