Another rather minor thing is that if you look at the source of their confirmation emails, they include a lot of reservation data in XML tags according to the schema.org specification (https://schema.org/FlightReservation). I was looking for a way to parse flight details out of confirmation emails before, and with Ryanair it is trivially easy to do because of this whereas with most other airlines you have to resort to parsing the plaintext or (awful) HTML.

Again, not a big thing but I was surprised that Ryanair seemed to be the only ones who took a standards-based approach to these emails.