For my current afghan, Cynthia's Afghan from Sally Melville's The Knitting Experience Book 3: Color, I made a replica of each square as I finished it. Here's an example, square number 29, with brick and chamisa as the final outer dark colors.
Then I used the collage function in Picasa to arrange the squares. Actually, Picasa chose a random arrangement. I just fine-tuned it to align the darks and lights with Sally's diagram. Then I put all the squares out on the guest bed and played switcheroo with them until I had a layout where no two colors were adjacent. If all this seems a little over-engineered, let me explain: Sitting in front of the computer doesn't strain my back as much as bending over the guest bed. I can move the little photo squares around much easier than I can move the actual squares. After I arranged the squares to my satisfaction in Picasa, I used the corresponding numbers to arrange the actual squares on the bed.
Yes, I tagged all the squares with a number. Believe me, those numbers were real sanity-savers. When I misplaced squares, I just referred to the layout and the numbers to find their proper position.
Now that all is arranged, I'm knitting all the squares together and adding the edging. Here's the layout collage.
And the actual afghan.
Off to the left in the photo above is my next project, one I couldn't resist starting before I finished this one. Taking a square that I didn't use because the colors layout was too different, I'm continuing the log cabin pattern with the leftover yarn. In the end, I will have a large square--I don't know how large it will be. I'm already thinking I might buy more yarn for it! Anyway, once it is big, but not as big as my Cynthia's Afghan, I will use it as a blocking/felting test. The pattern suggests that you full (slightly felt) the afghan by washing it and then putting it in the dryer on low heat for a bit. I think this rather rough wool will benefit from fulling. However, I am afraid that some of the darker hand-dyes may bleed. If I full the large square, I'll be able to decide if I want to full the afghan. Finally, here's a close-up.
And a link to the Ravelry project page.
My, those blocks are a bit askew. I definitely need to find a way to block it without having the colors bleed.