I recently build a dynamic generated SiteMap User Control for a multi site Sitecore solution translated in multiple languages. I wanted it to render links to publishable page items in two columns instead of just printing it out as a long list on the page.
I recently build a social media share function for Facebook, Twitter, LinkedIn and Google+ in a Sitecore CMS solution. There is also an add to favorites in Internet Explorer and Bookmark for Mozilla Firefox. The icons slides out when clicking the share-icon using jQuery toggle. The icons are all stored in one image using CSS sprite technique.