I recently drew about 30 sketch cards for the Topps "Star Wars Illustrated: The Empire Strikes Back" set. I got seven blank cards back to do with whatever I wanted! Here are the finished cards so far, with links to their auctions.
A few years ago, the talented artist Jake Parker started drawing and posting a pen-and-ink sketch every day during the month of October. Dubbed "INKtober", it's since caught on with thousands of artists around the world, sharing their creations on social media using the #inktober hashtag.
In 2014 I did an INKtober entry every day in October. Really proud of myself for finishing the whole set. Each piece had a Halloween, horror or sci-fi theme, in keeping with the season. I drew them all on custom 6"x9" bristol board, pre-printed with the INKtober logo and my own, and sold them all on eBay with starting bids at only $3.
I hope to do it again in 2015, but maybe starting the bidding at five bucks :)