Air Bases Search Engine: US air bases worldwide, location, maps, ICAO/IATA, official URLs
Example: Which US Air Force Bases are located in Great Britain?

Units Search Engines (one for each branch): units, nick names, tail codes, location, aircraft operated
Example: Which US Air Force units are stationed in Great Britain?

Tail Codes Search Engine: units, air bases
Example: What is the Tail Code of the RAF Lakenheath and which units carry it?

Link Directories (aircraft operating units): one for each branch plus one for superior organizations.