One of the things that Ann and Michael have done for the last couple of years is a BOTNS Summer Bingo reading challenge. Its a very relaxed reading challenge except that you have to read books within those categories and yes you do have a free space as to read whatever you like. The fun part of the reading challenge is that you can refresh your card until you get something that you feel you like and will also challenge you.
So this is the card that I chose this summer:
I think the ones that may be a challenge for me are the poetry collection, self-help (not a big fan of the genre), finding a book in which the protagonist/narrator is over 50 years old, and the obscure novel by a famous author.
So if you wish to join, you can head over to Books on the Nightstand (link goes to the relevant page), download a card and start reading. It starts May 25 (Memorial Day) and lasts until September 7(Labour Day). Good luck!