I’ve finally gotten around to adding free data downloads to OurAirports. You can now download nightly CSV-formatted data dumps of all the airports, countries, and regions in OurAirports at
http://www.ourairports.com/data/
These will open with most spreadsheet and database programs (make sure you import them as UTF-8).
All data is released into the Public Domain and comes with no warranty. If you have any corrections or additions, please make them in the spreadsheet and then send them back to me.
Land and Hold Short 
What country code is that you’re using? I’m guessing it’s ISO 3166-1 Alpha-2. Navaid.com uses FIPS 10-4.
Paul: Thanks right, it’s ISO 3166-1 alpha 2. That does have its issues (including slower ammendments when countries change), but it’s well-known internationally, while FIPS 10-4 is used mainly in the U.S. ISO 3166 is also well-known from domain names (modulo the UK/GB difference).
When you’re classifying the airports as Small/Medium/Large, what criterion are you using? The reason I ask is that it doesn’t seem to hold based on the length of the longest runway or the MTOW of the heaviest aircraft that can land there (for a few airports I know). Is it categorized according to traffic?
sidx: Originally, I used a variety of inputs to set a score automatically, including number and length of runways, published instrument approaches, possession of ICAO and IATA codes (IATA is worth more because it’s rarer), presence in the top 100 airports list, and one or two other things. I then set cutoffs for the three sizes. Since then, however, I’ve been editing some of them by hand, and I hope to open that up before too long. I think that they’re right most of the time, but some are obviously off by a category.