Sublime Text - Sublime Text is a sophisticated text editor for code, html and prose - any kind of text file. You'll love the slick user interface and extraordinary features. Fully customizable with macros, and syntax highlighting for most major languages.
SMath Studio - Tiny, powerful, free mathematical program with WYSIWYG editor and complete units of measurements support.
Netbeans - NetBeans IDE 7.0. Develop desktop, mobile and web applications with Java, PHP, C/C++ and more. Runs on Windows, Linux, Mac OS X and Solaris. NetBeans IDE is open-source and free.
PTC Mathcad - PTC Mathcad PTC Mathcad is Engineering Math Software That Allows You to Perform, Analyze, and Share Your Most Vital Calculations.
IntelliJ IDEA - Capable and Ergonomic IDE for JVM
EngineeringPaper.xyz - Online app for engineering calculations. Solves systems of equations, checks and converts units automatically, supports plotting, and allows for the creation of a link to share your work. Free and open source, no registration required.