There is one at the DriveThru sites:

It’s that time of year once again: Christmas in July is our single largest annual sale, set around July 25th, with participating products all on sale at 25% off.

This year, Christmas in July is being combined with the annual Summer Offensive sale on WargameVault and takes place from July 21-29.

So most titles on DriveThruFiction and DriveThruComics are discounted except the titles less than 30 days old.

As for the Smashwords site-wide sale, certain titles will be discounted until the end of the month: