Statistics about the world
http://data.worldbank.org/

Digital tunes
http://musicforprogramming.net

Catalog of data visualization
http://datavizcatalogue.com/

Fun – must seen
everybody wants to kill bruce

Translate every website in german dialects
http://www.burble.de

Online editor and compiler/interpreter for various languages
https://wandbox.org/

Statistics about the world
https://www.gapminder.org/tools/

Balance sheets of most german companies
https://www.bundesanzeiger.de/

The best way to get free https for your webpage – from start to finish in 30 seconds
https://certbot.eff.org/