Here's an interesting first pass at an enviro mashup for Google Maps: the Global Warming maps at X-Maps.com.
X-Maps appears to be a search interface for Google Maps (and just why Google Maps needs another search interface I'll leave as an exercise for the reader). Buried within the site, however, is a listing of well over a hundred different locations in the US that produce large-scale emissions of CO2; each entry reveals the tons of CO2 output in 2004, and links to a Google Map satellite view of the offending site. The vast majority are power plants, unsurprisingly.
Most states are represented, and it's perversely fun to search for locations nearby one's home or office.
It would be easy to criticize aspects of the map: they misspell "emissions;" there's no pointer to references for the data (although the numbers I checked at random roughly match other sources); there's no way to dig down for deeper info; the map and listing are forced into small frames, requiring a lot of scrolling around, even on a big screen. But as a hint at what a climate reportage mashup might look like, the Global Warming X-Map is definitely worth checking out.
Clearly, though, there's room to do this better.
Other good climate maps can be found at Maplecroft and the World Resources Institute's Climate Analysis Indicators Tool (CAIT) which "provides a comprehensive and comparable database of greenhouse gas emissions data (including all major sources and sinks) and other climate-relevant indicators." Just FYI.
Does anyone have a data set they want to have mashed up? It's not ideas that are difficult to have- it's the data!
Those other Climate sites are nice, but to be able to view the satellite images of those Smokestacks with the smoke coming out is AWSOME!!!!
By the way, I think the reason X-Maps.com has the search interface is because you can find Landmarks that do not have Addresses. I tried searching for mountains, rivers, hot springs, cliffs, beaches, waterfalls, etc. at Google Local, but I got NOTHING! X-Maps.com is the coolest mashup I've seen yet.
I also noticed that you can search out those Global Warming locations from the X-Maps.com home URL by selecting "Smokestacks" as the Category. You then just need to zoom in. Here's the search result: