Open Road Media has all their ebooks - including a lot of Barbara Hambly - on sale for 60% off for Monday only. (Do not know if it's USA only.) (Edit - poking about the Open Road Media site reveals inconsistencies between the ebook stores in markdowns; maybe worth contacting them to ask about it if you're not getting the Kindle versions, which seem to be the most consistent.)
Also, Weightless Books has three coupons going this week, from 50% off Small Beer Press and Big Mouth House books, to 25% off everything else. DRM-free ebooks in multiple formats.