In OurAirports, you can now tag airports any way you want, rather than just marking them as visited, and see a map for any tag. Here are two examples:

1. Canadian customs airports of entry (my tag “airport-of-entry”) Update: expanded to include U.S. airports of entry as well
2. Airports where I’ve done an instrument approach in actual IMC (my tag “instrument-approach”)

You have to be logged in to use this feature, then you’ll see a tags option in the right sidebar on each airport page. You can tag airports you’ve visited in different years or flying different planes; airports with good restaurants or flight schools; or anything else you want. Each tag is a single word, or a series of words connected by ‘-‘, ‘.’, or ‘_’, e.g. ‘fuel-stop’, ‘club-member’, ‘fees’, etc.

On the TODO list: rename a tag, to export tags to KML (for Google Earth), show most popular tags on each airport page.