Online Function Grapher

http://www.onlinefunctiongrapher.com/
Online function grapher is a 2D interactive function plotter. The online function grapher draws trigonometric, hyperbolic, log and ln, square root and other special functions like min, max, absolute value and many more.  Science and mathematics students often have to deal with equations and their graphical plots. While there are powerful desktop applications dedicated to this purpose, a quick web service for this task is the brilliant Online Function Generator, that lets you plot multiple functions on the same graph.

After The Deadline

http://afterthedeadline.com/
One of the best free tools that we can use to check our grammar and polish our writing is After the Deadline (AtD).  To check writing mistakes in a piece of text, paste the text inside the writing field and click the “Check Writing” button below. After processing the text, AtD will underline parts that it thinks contain mistakes. Click the underlined text to see the suggested correction(s) and/or read the explanation.

StudyDroid

https://market.android.com/details?id=com.studydroid.flashcards.free
StudyDroid is an easy-to-use flashcard application. You can get started very quickly making your own flashcards by clicking “add“. You can also make your own flashcards on your computer or you can browse the public flashcards at Studydroid to find something you like. When making your cards, it’s easy to change the text size or colour of the cards to make them more memorable.

History According to Bob

http://www.summahistorica.com/ Professor Bob Packett takes his history class and his considerable teaching experience online in the form of free history podcasts. He explains historic events from the perspective of those people who were caught up in it. He has a light style as he goes from explaining Caesar to more close events like The Korean War.

Hardcore History

http://www.dancarlin.com/
The well known podcast site by the American political commentator Dan Carlin takes an unconventional look at history with his own take on events past. Yes, you have to be in tune with his sense of humor as he rips into today’s society and relates it to historical churns. He covers topics on Roman history, the World Wars, and the Cold War to mention a few. The tag says it best – history like you have never heard before.