Just got an email for the Smashwords Summer Sale, which will run July 1 - 31:
https://www.smashwords.com/shelves/promos
For those who don't know (probably no one, but WTH), Smashwords has a couple of sales each year, where various titles are marked down anywhere from 25% to 100% with different coupons.
Smashwords has a pretty unusual selection of authors, many of whom are self-pub, but some of whom are authors who are self-re-pubbing previous conventionally published works.
It can be really hard to find things on the Smashwords site, so one trick you can use is to search this Deals forum for threads with Smashwords in the title, from past sales, and then check out the posts in the threads themselves for authors/titles that you might be interested in. Many of the same titles/authors go on sale in every sale, so if it was on sale in the past, it has a pretty good chance of being on sale again.
Anyway, enjoy...