This is by far my biggest (and most complete) personal project: A site all made to look up anything about the Japanese language, and learn it by doing a shitton of practices. This site was running for a long time in a closed alpha and beta test while still doing big improvements. Since this year is finally released in a public beta. The site is made for everyone who wants to learn Japanese, including myself. The content has been contributed and double checked by multiple people during the developments, but even now more content is added regularly.
During the developments my key point was to make the site fast and useful (nobody likes useless snail sites). The site has been written in ASP.NET MVC, but multiple tweaks were made to improve speed the user experienced while using the information site or the learn center. Caching is enabled on pretty much all areas possible (output cache, http client side cache, local storage) and the requests are kept to a minimum. The structure of the information pages are set up with html5 schematic elements to make our search engine friends happy.
Both the site and learn center is usable on a mobile device as well. I've used media queries to make the layout responsive and usable on any screen.
Nice tricks and technologies
I've also used the HTML5 speech recognition API and it turned out to be amazing for the practices! The API allows you to set up a few predefined text, which I've set to the vocab the user knows at that point. By limiting the speech recognition possible interpretations it (almost) always exactly knows what you were saying.
The site is ready to use but like always, my projects are a work in progress. Expect more of everything in the future... you know, somewhere between my other personal projects when I feel like it.