Nothing as interesting as many of the projects here, but I've had around 10k visits this month and plenty of returning visitors, so I guess it's useful enough. It's a very simple generator for static social media sharing buttons with support for Font Awesome: http://simplesharingbuttons.com/ Quite useful for mobile websites or email newsletters.
If I can propose 2 features:
1. I'd consider adding sharing services (e.g., we use addthis). The major plus is that they track analytics for each share.
2. Twitter also supports the "related" intent to propose followers after sharing. I think that's pretty useful (and in general it's pretty hard to configure in the before mentioned services ;)