I use short lengths of leftover moulding to build small boxes that I sell in the gallery for gifts. {The business card holders have sold well for the past 7 or 8 years!). The really short lengths I use (contrary to alot of framers' opinions) for starting campfires. You don't need but a handful of these to get a roaring blaze started. You can also use short lengths for push sticks on your table saw and other woodworking tools by cutting a little notch in the squared end. A flat shallow moulding works best for this and I have ripped down thicker mouldings for this also.
Foamcore has alot of uses:
Filler boards on small framings.
Pads for an underpinner.
Supports for frames when underpinning them. (see another thread for an example of this).
Little boxes to store things like WallBuddies and their hangers, screws, etc.
You can blend nail hole filler on scraps of foamcore when matching a shade that needs a couple of different colors to match.
Table top "steps" can be built out of foamcore and covered with suede cloth or whatever draped over them for nice stepdown displays for jewelry and small gift items.
I even stuffed some foamcore strips in the back door crack of my shop until the guy came by to weatherstrip it last winter!
My next door business neighbor runs a flower shop and she uses foam core blocks to stick her arrangement pins in when she is doing a wedding or other floral arrangement. (I refer to her as the "dumpster diving flower lady"!)
Mat cutter blades can be used for trimming dust covers if you buy one of those little red trimmers. I also use mat cutter blades for finishing off the vertical cuts in thick foamboard when trimming excess off of a drymounted poster. Leave the cut in place on your mat cutter and go through it with a pass of the loose mat cutter blade and it makes a nice clean cut. (My C&H never seems to cut completely through 3/16" foamboard for some reason.)
Little plastic pin boxes that stainless steel pins come in make nice gift boxes for jewelry after a bit of cotton is placed in them.
The foam and bubble wrap that moulding comes wrapped in from many distributors can be used for all sorts of things. Use your imagination on that one.
I get one delivery from a moulding distributor that has to come UPS and they stuff the box with plastic mat bags. (Already one use for recycling) I use them for the same things that others have already stated.
I have a bunch of others but this was a few of the ones that I use frequently.
Framerguy