I just re-installed Maltego (haven't used it in years). Here is quick run down for you, once you get it up (you need to register an account, and then open it as the "Community Edition") make a new blank Graph. Then go to your browser, click and drag the URL (for example the hacker news site) from you browser into the Maltego Graph (the big empty white space). Right click the icon that just appeared, you might be tempted to click "Web Technologies", this is mistake and won't get you the info you are after. Instead click "All Transforms" and click "To Website [Convert]". You will get a new Icon that looks like a monitor with "WWW" on it. Right-Click on that and now click "To Web Technologies [Built With]". You get a whole bunch of information here, you kind of have to sort things out a bit yourself at this point. However, that said you can see one of the things it lists for the Hacker News site is "ArcGIS". A quick google search for "what is hacker news built with" confirms.

>Hacker News (sometimes abbreviated as HN) is a social news website focusing on computer science and entrepreneurship. It developed as a project of Graham's company Y Combinator, functioning as a real-world application of the Arc . programming language which Graham co-developed.

Maltego is pretty fun program, you can learn a lot with it. Viewing the tracking codes for a site can often reveal other sites a company owns, as a lot of companies are lazy and end up using the same tracking code on all the sites they own.