I have just recently done exactly that - one big log cabin block by simply adding piece after piece! It was a wonderful experience and I highly recommend just letting yourself go with it......I didn't worry too much about the colors as all colors blend eventually. I did stay with smaller patterns as that's what was mostly in my scrap bin. It's going to a friend and she's anxious to have it finished and in her possession.
Sorry I cant post photos - my camera is back at the manufacturer for repairs!