There is an enormous amount of data in the world that contain a spatial component and are just begging to be mapped. If you use your imagination, you should be able to come up with an interesting idea that is suited to your ability. But just in case you're not sure of what you'd like to do, I will list some ideas that I came up with. They are generally in order of increasing difficulty.
The National Geophysical Data Center (NGDC) of the National Oceanic and Atmospheric Administration (NOAA) maintains databases on the occurrences of earthquakes, volcanic eruptions and tsunamis:
Earthquake Database (http://www.ngdc.noaa.gov/hazard/earthqk.shtml)
Volcanic Eruptions Database (http://www.ngdc.noaa.gov/hazard/volcano.shtml)
Tsunami Database (http://www.ngdc.noaa.gov/hazard/tsu.shtml)
Each database includes the latitude/longitude coordinates of the event along with other descriptive data. Importing the information into a MySQL database and providing a GUI for the selection of subsets of the full dataset should be relatively straightforward.
Features from the USGS Geographic Names Information System (GNIS)
The U.S. Geological Survey (USGS) maintains a database of geographic features called the Geographic Names Information System (http://geonames.usgs.gov/pls/gnispublic/) and provides public access to it through their website.
The database includes natural and man-made features ranging from airports to lakes to woods. While the site makes it possible to plot an individual feature on a Google Map, I don't see a mechanism for displaying all features of a certain type in a certain place. Thus, it seems to me that this database offers the potential for lots of interesting applications.
If this idea interests you, here is a tip on retrieving the data you want: Select a feature type, then a state and/or county and click Submit. For example, I selected cemeteries in Pennsylvania. The features and their coordinates will be displayed in a table. Some queries (such as mine) may take a minute or so if they return a large number of features. Beneath the table is a Save as pipe "|" delimited file link. If you click this link, you can import the data into Access or Excel and specify that the pipe character separates the values.
Global airport database
This database contains the locations of major and minor airports around the world (http://www.partow.net/miscellaneous/airportdatabase/index.html). It is maintained by an Australian software engineer. I agree that seems like a strange place to find such a thing and I don't know if there is a more authoritative source out there.
At the bottom of the page is a link to the zipped data file itself. The values in the file are separated by semi-colons.
A very simple application would be one that allows the user to select a country/state and see all of the airports in that location. To go a bit beyond that, it might be possible to construct links to sites that provide information about the airports. Or perhaps there are web services that provide interesting information. For example, here is a site that makes it possible to find airports served by a particular airline, airports currently experiencing delays and current weather conditions (http://www.flightstats.com/developers/bin/view/Web+Services/web_services...)
These services are not free, but they can be accessed using an evaluation account that is probably long enough to complete the project.
One application of this dataset might be to allow the user to select a year and/or basin and view the hurricanes associated with that selection. The track segments could be symbolized based on the hurricane's intensity.
NOAA is once again the source for this idea. Their Storm Prediction Center provides public access to reports of tornadoes, hail, and high winds. The reports are comma-delimited and are accessed through URLs like the following examples for May 1, 2009:
Tornado Report for May 1, 2009 (http://www.spc.noaa.gov/climo/reports/090501_rpts_torn.csv)
Hail Report for May 1, 2009 (http://www.spc.noaa.gov/climo/reports/090501_rpts_hail.csv)
Wind Report for May 1, 2009 (http://www.spc.noaa.gov/climo/reports/090501_rpts_wind.csv)
My idea here is that the user could choose a date (or range of dates) and one or more weather type to map. The application would then read and plot the data from the appropriate files.
Each year, the National Center for Education Statistics (NCES) conducts a survey of public schools throughout the U.S. to compile what they call their Common Core of Data:
This rich dataset includes the name, latitude/longitude, enrollment figures by grade, gender and ethnicity, and more. One idea for this dataset is to allow the user to select a state and county and see all of the schools in that locale. The schools could be symbolized by their type (elementary/middle/high).
The reports include the city where the sighting occurred along with the date/time on which it occurred and some descriptive information. Because they lack coordinate information, the reports would need to be geocoded before they could be mapped. An application based on these reports could allow the user to select a date (or range of dates), a state/country, and/or a shape (disc, triangle, cylinder, etc.).
This is certainly not an exhaustive list. If you have an idea for a good application, but aren't sure where to find the data, I encourage you to search the web. You may be able to find a site that provides easy access to the data you need by doing a search that combines the data's theme with terms like "web service," "data feed," or "XML."
Move on to the next page to find more details on the project requirements.