Standard packages for compact SMT crystals
There are few common packages for crystals. For 4 pad variants, there is 5x7mm, 3.2x2.5mm 2.5x1.6mm and few others. They are available from many different manufacturers and share a common pinout.

For 32.768KHz crystal (Very common in microcontroller based designs) there is a common package from Citizen (Watches) that is used by many other manufacturers, but I dont know its dimensions off hand.