Note: An old unpublished post; publishing now…
Every day a new technology or a programming language emerges in software industry. Keeping an eye on them, learning them and being an early adopter is an immense task; especially if you are in the software development community. Google does help me in finding the relevant links, however either they are specific to the subtopic or they cover the topic partially. (just a thought – Ganapati Bappa Morya is a popular slogan these days on account of Ganesh Chaturthi. For a software professional Google is the new God – Google Bappa Morya!)
http://www.w3schools.com is the best when it comes to knowing about the new technology in a nutshell. I would strongly recommend it to students and the beginners.
One thing I particularly like about w3schools is they have a Tryit Editor where you can edit and view the results instantly on the same page. For example, in this link http://www.w3schools.com/html/tryit.asp?filename=tryhtml5_video_bear you can edit the source code and view the results instantly.
Being a Microsoft .NET developer primarily working on C#/VB.NET, you can tinker around these languages online at https://dotnetfiddle.net.