Mini Challenge

I am going to be hosting a mini-challenge, and although I have a couple of ideas, I wanted to see if you had any ideas that you would like to see for the topic.
It can be a list, top 5, questions, anything that could be classified as a mini-challenge!

As an extra incentive, if you submit and idea, you get a chance for an extra entry in my Welcoming the Fall contest (2 chosen by Random.org, and you may submit up to 3 different ideas), and if I chose your submission for my mini-challenge, I will give you 5 extra entries.