Is there any way that I can sort images by resolution?

apple's aperture can sort by pixel sizes. pixel sizes are in the form ###x###, and it sorts according to the first number. i don't know if aperture is best for what you are trying to do, but it can sort by size. there's also a trial version of aperture that you can download and use for 30 days.

more information about aperture: http://www.apple.com/aperture/

since a higher resolution will also result in a larger file size, couldn't you just sort all the files by size?

The only other thing I know of is in Graphic Converter ---> print catalog. This gives you the option of printing by resolution.

But who knows - in the dark labyrinth of many passages that is Graphic Converter Preferences, there might be something else.

You can do this in Finder. If you cntrl+click on the saved search query folder for images you can add resolution (width and/or height). All Images> Show Search Criteria>click on the "+" sign click on the drop down list on the far left select other if you check the box to the right (In Menu) that criteria will show up in the list. I use 4 resolution criteria to eliminate small files when do a "random" search (greater than but less than). You can also save a new "smart folder" with the criteria.