I just bought a 24" ACD, and I love it. However, because my MacBook Pro is only 1440x900 resolution, if I resize anything it'll go out of proportion on my MacBook Pro screen. Ideally, if there was such a program, I'd love to be able to have my windows set a size and position for 1900x1200 resolution, and for them to have a different size and revert to that when I use my MacBook Pro's 1440x900 display. Does that make sense? I just don't think I can be bothered having to resize Safari, drag any windows that were over on the right hand side of the 24" display back over on my MacBook Pro display just to see them when I unplug the 24". I'm sure it wouldn't be too hard to make an application that does something like that - just take note of the window positions and sizes for both resolutions and switch between them when the resolution is changed.