Google revolutionized the online map world when it launched Google Maps. Another revolution is brewing with a Firefox extension called GreaseMonkey. GreaseMonkey allows one to client side JavaScript scripts which can modify various aspects of a web page (gross oversimplification). Combine the two and you get things like the Craigslist-Google Maps mashup of a couple weeks, and now this: Chicago Transit Authority map on Google Maps which combines Google Maps and Greasemonkey to add a CTA map option.

What I find fascinating is that there's a growing ability of interested and incented users of web sites to customize (and in theory improve) the user experience of a web site. Now, the ex-Corporate Web thug in me is a bit horrified at the notion that users can change the experience of my web site without any intervention (and perhaps, any control at all) on my part. On the other hand, it's a nice example of one of the lessons of Internet and networked technologies: routing around the problem. If your user experience sucks but your customers are interested (your site apparently has some value to your customers), then they will tailor, fix, and change your site's user experience to their benefit.

Now, there's several drawbacks, the biggest being that this only works with Firefox. I use Firefox almost 99.999% of the time on all the platforms I use, however I know that most of the world is still stuck with Microsoft Internet Explorer. Second, I think there is a subtle danger to web sites which are extended in this manner in that people tend to forget where they get such modifications from. If the code stops working with your site, for whatever reason, more likely than not you'll get blamed, not the developer of the code. It spreads the maintenance burden of your site beyond the factors you can control. This isn't a bad thing in and of itself, it just adds to the burden of running a web site. A compromise: if your clients, customers, users of your web site are finding such extensions to be valuable, endorse them and make them a formal part of your site (to the extent possible depending on licensing restrictions, phase of the moon, temperament of your Corporate Communications execs, etc.).

The revolution isn't Ajax, it isn't XMLHTTPRequest, it isn't Greasemonkey; it's the movement of interactive application functionality to the user's desktop. It's not new, Flash and Java have been able to fill this role for years, but they have always operated in a different space from the browser. You know when you're using a Flash or Java application, you see it load, you take the hit to download the JVM or player. Netomat tried (is trying?) to fill this niche but hasn't taken off. What I see in the combination of Firefox, Greasemonkey, and Ajax is the creation of a new platform for rich networked applications, which can enhance and extend the user experience of existing web sites with minimal revision on the part of the web site maintainer. To successfully take advantage of this platform web sites will need to be more XML/XHTML compliant since the pages need to be parseable and well-formed.

My interest as well is in the push of interactive application functionality from the server, where it doesn't belong, to the client. This allows servers to focus on serving content, and processing data; not on maintaining state information, trying to work around all the possible ways an interactive experience can be broken by splitting display off from application processing.