(History here, here and here.)

The Details
Pattern: Purl Bee Granny Square Tutorial
Hook: size J (US)--because it's what I had on hand and it seemed to make about the right fabric with bulky yarn and worsted yarn doubled.

Yarns: A whole lot of different scraps, leftovers, and unallocated yarns from the stash, all bulky weight or doubled worsted weight.
Knit Picks Decadence (burgundy, brown); about 5 skeins each (1000 g total)
Knit Picks Andean Silk (olive--from traveling cables cardigan); about 4 skeins (200 g total)
Lion Brand Kool Wool (beige, dark green, red); about 9 sks beige/2 sks green/1 sk red (600 g)
Lion Brand Fishermen's Wool (brown--from Aran Cardigan); about 1/3 skein (75 g total)
Filatura Lanarota Puno (beige--from Mom's Christmas sweater 2007); about 4 sks (200 g)
WEBS wool tweed (banana); about 4 sks (400 g total)
Rowan Soft Tweed (green--from Tahoe); about 4 sks (200 g)
Debbie Bliss Luxury Donegal Tweed (green--from Mossy); about 4 sks (200 g)
Lana Grossa wool (green--from Knitting For Peace messenger bag); about 6 sks (300 g)
Araucania Atacama (green mix); about 8 sks (400 g)
Cascade Eco Wool (brown--from Not So Sahara); about 1/2 sk (100 g)
Elsebeth Lavold Classic Al (green--from Opulent Raglan); about 6 sks (300 g)
Malabrigo Worsted (dark green--from Central Park Hoodie); about 1 sk (100 g)
and
Cascade 220 Wool (burgundy); about 8 sks (800g)--just for the border!
If my recollections and my math are correct, this adds up to 4875 grams of yarn, or about 10.7 pounds! This is a biiiiiiiig blanket. I have a king-sized bed, and as you can see, the blanket drapes well over the sides. Although it's hard to get an accurate measurement of something so stretchy, it measures at least 108 inches--or nine feet--square.

But it's soft and pretty and used up a whole lot of yarn I would never have used otherwise, so all in all, I call it a great success!
Now, where did I put my knitting needles?