Community-powered portals are on the rise. We have seen plenty of them such as Imgur and Piccsy in the past. Running sites of that magnitude does take a lot of money and effort. You can always try to clone their functionality though. FacePress is an attractive theme designed specifically for user-powered content sites. It has a professional design and multiple layouts to help your community grow faster.
FacePress looks quite slick. It has multiple views so your visitors can go through the latest submissions on your website easily (timeline, grid, and list views). It has multiple skins, so you can use this for your portfolio, image gallery, and classic photo blog too. This is made for communities though. Your users can follow others if the option is enabled. Full-width, and fixed size layouts are available as well.
Registered users get to edit their profiles, including their personal data and avatar. Webmasters can enable front-end submitting. Images, videos, audio, and text content can be uploaded in the front-end. FacePress has unlimited sidebars and offers custom widgets so you can present your content the right way. FacePress also provides breadcrumbs, shortcodes, and related posts.
FacePress for WordPress is a pretty cool theme for communities. It makes putting together a content sharing site easy. Do yourself a favor and make sure you have a decent host before putting up such a site.