Tommy....although my stats follow yours pretty closely for sales, the other thing Ive noticed is that around the 1st and 15th are peak days for sales for me...must be the military and others that get paid on the two week plan
although that usually evens out in the fall with the new college kids getting online
<added> thats for the LL anyway - the rest of the sites change so frequently based on SE listings and other factors that they just stay overall steady