Compress all textures on build

Some of my textures are fairly large. Obviously I can go through each one and shrink it in photoshop, but this takes time and I want to have different sized textures for each device I export to. When I used to make Flash games there was a global compression quality in the settings that was really useful - is there such a thing in Unity?

select all textures you want to compress in Project tab and change values in Inspector