As the Gulf oil spill continues to spread, where it is, where it's going, and what effects it might have are a growing concern to more parts of the US. Maps, data visualizations, and infographics are key tools for telling this story. Here's a roundup of useful resources. (Several of these are already mentioned on SEJ's Daily Glob blog .)
1. NATIONAL OCEANOGRAPHIC & ATMOSPHERIC ADMINISTRATION (NOAA)
- Environmental Response Management Application: NOAA's "GeoPlatform" beta service  is a bit clunky and wonky, but data-rich and useful to journalists. It's intended to assist emergency responders and environmental resource managers who deal with incidents that may harm the environment.
- NOAA Office of Restoration and Response, Deepwater Horizon incident:  Features daily maps for beach closures and the trajectory of nearshore and offshore surface oil. Also includes current wildlife death/stranding counts and more useful statistics.
- Field guide to NOAA trajectory maps. 
- NOAA Gulf fishery closures  (maps and more).
- NOAA Satellite and Information Service, products and operations involved in response to Gulf of Mexico oil spill:  More detailed (and geekier) data and tools. Could be useful for map mashups, interactive multimedia, or infographics.
2. DEEPWATER HORIZON JOINT INFORMATION CENTER
- A collection of maps and other resources  from the "Unified Command" made up of several federal agencies and BP.
- Media gallery  (photos, video, animation, audio, maps, etc.).
- Flickr photosets. 
- YouTube channel. 
- Facebook. 
- Twitter. 
- Involved agencies and organizations. 
- June 7 Coast Guard illustration of Deepwater Horizon response efforts  so far (high-res, large file).
3. ENVIRONMENTAL PROTECTION AGENCY
- EPA response to Gulf oil spill:  In addition to imagery and news updates, this site includes Google Earth map layers based on data from ASPECT, "a twin engine aircraft designed to assist in the collection of air sampling data as well as photo documentation of environmental incidents." Also features air, water, and sediment monitoring datasets.
4. STATE OF LOUISIANA
- Governor's Office of Homeland Security and Emergency Preparedness: Gulf oil spill projected trajectory maps  (Google Earth) and Flickr imagery. 
5. GOOGLE CRISIS RESPONSE
- Gulf of Mexico Oil Spill:  One of the best parts of this collection of resources is the list of Google Earth map layers (kml files) created by a wide range of sources, addressing many different topics. If you use Google Earth (and every environmental journalist should), then the map layers here can be the basis of animations, still images, and other kinds of imagery that can enhance reporting (Be sure to double check the date and source of information for each kml file.).
- This site  also supports YouTube video uploads of oil spill-related videos (most about the recent Gulf spill, some on other spills or spill-related issues).
6. NATIONAL AERONAUTICS & SPACE ADMINISTRATION
- NASA Oil Spill Imagery:  One of the most telling ways to view the Gulf oil spill is from space. Many divisions of NASA have been generating compelling, free-to-use satellite photos, data visualizations, charts, articles, backgrounders, news updates, and more about this disaster. On Flickr. 
- See how National Geographic used some images  from NASA Goddard to explain the spill's evolution.
7. LOUISIANA BUCKET BRIGADE/TULANE UNIVERSITY
- The Louisiana Bucket Brigade,  a citizen anti-pollution group, has combined with GIS students at Tulane to produce a crowdsourced spill crisis map. This project, based on the open-source platform Ushahidi, allows people from all along the Gulf coast to file location-identified reports (text, photos, video, audio) by mobile phone or computers. The quality, usefulness, and reliability of individual contributions vary — but on the whole this project provides intriguing insight and excellent engagement potential.
8. AMERICAN BIRD CONSERVANCY
- This wildlife advocacy group mashed up their own info  about Gulf coast bird habitats with NOAA data about the spill to create a static-image map showing which kinds of birds might be affected, and how. Their resource page also includes a list of critical bird habitats most at risk from the spill — which could be useful for additional data mashups.
- ESRI corporation, the dominant producer of GIS software, has produced a set of Gulf spill interactive maps:  Map layers based on social media postings about the Gulf spill, an animated timeline map, and an economic impact map.
- This environmental advocacy group  uses "remote sensing and digital mapping to educate the public and policymakers about the environmental consequences of human activities, and to hold corporations and governments to higher standards of accountability around the globe." They used government aerial maps to produce a more accurate estimate of oil flow at a time when BP, the federal Incident Command, and the traditional news media were shirking this duty. News media picked the story up from Skytruth.
- Ushahidi-powered crowdsourced Gulf oil spill tracker map.  Flickr photosets.  Blog. 
11. THE GULF OF MEXICO MESS (pipeline map)
- This useful map of Gulf of Mexico offshore pipelines and oil/gas rigs  by Matthew Baker, May 27, is based on data from NOAA, State of Louisiana, MMS, ESRI.
12. BP SITE
- Gulf of Mexico Response:  BP's own information about the Deepwater Horizon incident, spill, and efforts to cap the well and clean up the spill. Numerous resources in many media. Also includes links to BP's state-specific spill-related sites.
13. NEW ORLEANS TIMES-PICAYUNE
- NOLA.com 2010 Gulf of Mexico Oil Spill topic/resource page:  Aggregating all stories and interactive/multimedia coverage (including maps and infographics), as well as a public blog.
14. NEW YORK TIMES
- NY Times interactive Gulf spill map:  Notable for its prominent explanation of assumptions made in creating the map from data, and for highlighting differences in estimates of the spill size. Clarifies that there's not just one set of data to look at, nor just one way to look at the data.
17. SOCIAL MEDIA: PHOTOS AND VIDEOS
- Flickr:  Creative Commons-licensed images taken after April 20, 2010 that mention "oil spill" in the tags. (Note: double-check sourcing on these, sometimes CC license is claimed inappropriately.).
- YouTube videos tagged with BPOilSpill. 
18. IF IT WAS MY HOME
- Data visualization that maps the Gulf oil spill area on a local map  produced by scanning the user's current internet IP address. Independent project by Andy Lintner. Map images generated by this site are being used by many blogs and news organizations. A similar project by Paul Rademacher  uses Google Earth.
19. VARIOUS DATA VISUALIZATIONS
- Egregious citations issued to BP  (by Nathan Yau). Based on info from the Center for Public Integrity. 
- In Deeper Water  (from Information is Beautiful): Simple infographic comparing size of Gulf spill to earlier oil spills. Notable for also publishing spreadsheet with supporting data via Google Docs. 
- Whose Oil Spill is it Anyway?  Blog post by Microsoft scientist Matthew Hurst. Points out that several companies (not just BP) bear some responsibility for the Gulf spill. One graph compares how often each company has been mentioned in blog posts about the spill (overwhelmingly about BP); another shows stock market reaction for each company (more evenly distributed).
20. NATIONAL HURRICANE CENTER
- So far this NOAA site only has an FAQ document  about how hurricanes might interact with the oil spill. But over the coming hurricane season it's likely that usual Gulf hurricane maps and imagery  will be augmented to include special spill-related information.
21. GREEN BLOG (NY Times)
- Gulf oil spill resource list.  Includes maps, infographics, other info. Updated regularly, and takes reader suggestions.