Is there any way to save frequently used expressions in the selection or field calculator dialogs? Obviously I can cut and paste them into a file where I might save them, but I mean within the context of QGIS like you can do in ArcMap.
This is not possible at the moment. There is a ticket for it, and assigned to me no less :)
It was in my original plans just never got around to it.
I don't think I will have time for 2.2 but maybe 2.4.