So I started learning Calculus a while ago and having this online derivative tool is very useful! Especially since I’m going to get an iPhone 😀 (I haven’t ever not mentioned that in posts)
Easy to use and operators and all that is intuitive:
Online Derivative Calculator.
Parent Site with other Math Tools
This here is a keyword tool to generate a list of keywords based on text that you copy and paste. It also prints the keywords in a comma-delimited list so that you can just copy and paste it as tags in WordPress. Very useful and easy to use.
Keyword Suggestions Tool