This section of the site contains links to freely-distributable navigation information for pilots and simulation enthusiasts. Sadly, there is only limited information available for outside the U.S., and most of that still comes from the U.S. government itself.
An explanation of the Maximum Elevation Figure (MEF) on Canadian and American VFR navigation charts, and why there seems to be a safety margin sometimes.
The DAFIF contains an enormous amount of world-wide air navigation information in both fixed-field and tab-delimited format, including airports, runways, approaches, airways, air traffic services, and much more. This site also one of the few sources for free approach plates for airports outside the U.S. (though the selection is not complete).
Paul maintains a large, free database of worldwide airports and navigation aids and publishes the database in formats for several different flight-planning applications and in a portable XML format called GPX. This information is suitable for building basic GPS aviation databases. Paul's data comes from both official sources like the DAFIF and NFDC databases and from individual contributors.
The FAA's National Flight Data Center (NFDC) produces a complete navigation database for the U.S., including many airports missing from the DAFIF. The database is redistributable, but the FAA does not publish it online. Fortunately, some kind people do subscribe to the information and then publish it in online mirrors like this one and this one.
These are the same approach plates that the FAA's National Aeronautical Charting Office (NACO) publishes in its official, easy-to-rip newsprint editions. All of the approach plates for the U.S. are available through this site in high-quality PDF format.
The FAA produces high-resolution scans of its VFR charts (typically around 50 MB each) but does not release them online. They are available, however, through aviationtoolbox.org.