Check out the Missouri Star Quilt Company tutorials on YouTube.

In my house fabric scraps, dust bunnies and cats all seem to multiply at an astonishing rate. :D I just finished a postage stamp quilt that did not even leave a dent in my scraps!

put 3" in a grid, 4 deep and as wide as you want your quilt (X), the 5" in a 3 by (X) grid, and finally, the 8" in a 2 by (X) grid...then set sashing in between (just horizontally) to unify, do at least one (border or more) and you will have an eco-friendly, easily done, modern quilt top....if the widths come out a bit different, just center each grid and trim the outside edges to the exact inches you want.

I chose depths that would come out roughly the same, 12", 15", and 16", but of course, they would be equally attractive to vary the depths, too....say a 15 and 16 separated by one row of the 3"? or vary them up and down the whole length, a 15, then 3, 10, 3, 8, 3, 16, 3, 10......maybe easier to sew each size 1 block deep and as wide as you want them, then play with 1 of these, 2 of those, etc., till you are happy with the look, then put in your sashing strips, again, horizontally, and you're good. If you have lots of colors involved, your sashing (solid or tone on tone) should just be whatever color you want to be dominant...there will be something in that many prints that will pick up your color and look 'planned.'

Sort them by sizes, and find a background color for each size, then cut squares to match your scrap squares. Layer, draw a line and turn them in half-square triangles. Search HST quilt ideas on the internet. You will be amazed at how much fun you will have with your squares. Did this with my guild and everyone came up with a different pattern with just hst. Enjoy

Falling Charms quilt calls for 5" squares and 2.5" sashing strips. I just made one and it was really easy and fun. Here is the Youtube video for it:
http://www.youtube.com/watch?v=4KkpbFKBaKA

I'm thinking the same pattern would work great with 3" squares and 1.5" or 2" sashing strips.