Hi, I am not sure, whether this was discussed before. After switching to Mac OS X I discovered a nice feature in Pages.
Pages and Keynote has some kind of automatic guides which shows up and let the object snap in, when it has some special relation to a neighbour object. I also saw this in OmniGraffle. If I a have a frame and create a new one, move it around on the page: When the object aligns with its center to the other, a line appears and I can just drop the object, it will snap so that both objects align with their centers. This works horizontally and vertically. You can work faster if you quickly want to layout something. juh
