I created lexical.io as way to learn more about web programming. You'll notice some rough edges as it's my first 'big' project, but for now I'm happy with how it is and I hope some of you find it useful.
The idea is similar to sites like readlang.com, where you submit a text and then can click on words for more information. Wikipedia and Wiktionary are the two sources of data, plus a number of additional audio recordings. There is an option to select your native language (currently 8 languages are supported) and then lexical.io will return Wiktionary translations and Wikipedia abstracts in that language. I can vouch that it works quite well for Spanish and German, but for languages like Korean with smaller amounts of data it may be less effective.
Given more time I would like to add more languages and potentially include target languages beyond English. There are many other features and improvements to be made, but first I'd like to see what people think. Any feedback is appreciated!
(P.S. I haven't had time to record a screencast video explaining the features, so right now the video on the about page is a dead link)