Here's a link to my crumb and string quilts on webshots:
http://home-and-garden.webshots.com/...78030079qxCABm
My definations are:
Crumbs are those pieces at least 3/4" but not very long.
Strips are the trimmings that are at least 3/4" wide and usually WOF, or big enough for the block I'm making.
Scraps can be any size that are leftover from the last project completed, or accumulated from someone elses finished project. For me it's usually less then 1/3 yd or so but that's open to interpertation also.
Really it's pretty much all what you want to classify when you get down to the details.