Progress bars have once been very popular on the internet and you used to see them on a lot of sites at that moment exclusively for loading a site. Since then, designers avoided them a lot, until, once again they became popular. Nowadays, they are not used only for loading a site, but rather an inner page, a video, a song or various other purposes.
The new rise in popularity is also caused by the use of jQuery and CSS3 which are making these really cool design elements easy to code and implement within a site without using Flash and causing the site or page to load incredibly slow.
Enjoy these 46 lovely progress bars and subscribe to the site via the social media accounts if you want to see more design inspiration like the article presented here.