ID90's are almost dead. As Doors to Manuel stated ZED tickets are the game and thankfully so (although it remains to be seen how flexable they remain, compared to now, after everything goes electronic by the end of March 2012). Our airline mostly has ZED agreements but only a very few ID75 agreements which is quite expensive.
Yes, I worked for an airline previously which gave free ZED tickets on own airline (you paid the taxes). That was a concession negotiated with the union to lessen the pain of the pay cuts and furloughs after we emerged from bankrupcy protection. I would have preferred to pay for the ZED tickets and not have gone through an involuntary loss of employment.
Keep in mind that if you travel to North America or through Europe a substantial portion of your ticket price is taxes. The breakdown is clearly listed in your ticket.