Here are 2 digital distributors steam and Humble Bundle (links further down).
Lets talk about there cut of the funds raised.....
Steam - They take around 30% after tax of your monthly sales, they also might add extra charges that are talked about when you first get passed the green light stage.
Humble Bundle - These take 5%, thats it just 5% of your monthly sales you host the game from your website and sell it by there widget.
Humble Bumble store - If selling through there store they take 25% of your monthly sales but give 10% of that to charities.
https://www.humblebundle.com/developer
Summery:
It would be great not only to include the steam SDK into skyline but also the Humble Bundles API Located at http://developer.humblebundle.com/
If your cleaver you would use both companies to distribute your game as they are both known world wide.
