These are some of the software that I really found helpful while I was pursuing engineering. Most of these software are unheard of especially to the people who are not from engineering background.
LateX (pronounced Leh-Tek) download Irritated by all the formatting that needs to be done in MS WORD? Atleast I was when I was writing my thesis or papers, and the formatting of the document took far more time than writing the essential data. This is where LateX scores, a powerful, efficient, and high-quality typesetting document, you just type your data and let the LateX system handle the formatting stuff for you. Now LateX is not your WYSIWYG(What you see is what you get) application like MS WORD, but if you are working on your thesis or project or writing journal papers then this is probably the best software out there and its free. You can easily set up the whole system using this tutorial. Though the whole system might look a bit daunting at first and with lots of hassles but I assure you that once you get acquainted with it, you will never use your MS WORD again. There are various templates available online for thesis, journal papers, resumes etc. which can be downloaded for free and used for writing all these stuff without worrying about the coding stuff. Still if you are facing problems, then the LateX community is very very helpful and I am sure all your problems will be addressed in just a couple of minutes.
FreeMind is a free mind mapping software written in java, lets you organize thoughts on a page as they connect to each other and to the larger picture. You can also organize your class notes and other course works after all learning using mapping can is far more efficient than just cramming everything. FreeMind encompasses a fine range of features, including scads of icons and color formatting options to help you visually organize concepts. It also supports hyperlinks, which allow you to link Web sites and even documents to a map. In addition, you’ll be able to export your landscape of thoughts in a variety of formats, including HTML, PDF, and JPEG. As flexible as it lets your mind be, FreeMind works within an older-style logical structure that could get frustrating for some, but all in all I do believe it is very useful in preparing notes, visualizing a project or a process. A 10 min tutorial on how to use freemind is available on youtube.
Oracle VM Virtual Box is one of my favorites. It is the most popular virtualization software available and its free. You can download it and install it on your existing platform, and start creating and running virtual machines alongside your existing applications.
Example: Installing Ubuntu on virtual box and using it alongside your windows 7