I spent a short amount of time writing a fairly crude Twitter bot in Python, using Tweepy. It listens to a stream of tweets, looking for ones with keywords like 'win', 'RT', and 'fav'. After passing through a couple of filters to try and determine if this is a genuine competition tweet, it will follow, favourite, and retweet.
It's been running for just over a week now and I've won a few things, most of them digital so far, and all of them pretty much worthless. Included in my winngs are: A random Fortnite account, a cupcake from a stand in Manchester, Grave Danger for PS4, Fear the Wolves beta key on steam, the book 'Fliers' by Laura Mae, and an entire £0.05 sent to me on Paypal.
He said it was meant to be £0.10 but the Paypal fees were too large.