Inkscape
Inkscape is an open-source SVG editor. Vector graphics have many advantages over pixel graphics that can be done with e.g. GIMP, Paint etc.
I had to draw several diagrams for my bachelors thesis, and I found Inkscape offers lots of functions that make it suitable for that:
- alignment of different objects
- drawing perfect squares / circles (press Ctrl while you draw the shape)
- (very important!) export to PDF and PNG format
The only thing I feel it lacks (maybe i just haven't found that function?) is something modern pixel graphics programs have: multiple layers. But apart from that, it is perfect for drawing diagrams etc. especially when you will need to scale them, as SVG is scale-independent.
Skype / VoIP
because Instant Messaging and mailing sometimes is not productive enough. I spared so much time in university by communicating with my fellow students through Skype, it's ridiculous. Which medium is best for your communication really depends on your task, but sometimes calling someone is just better than messaging!
Cygwin
Yes, i'm still a Windows user, but i can't live without my shell anymore. I do most things through my IDE or some GUI, but often enough, something needs to be automated through a script, and then i open up my cygwin shell and just love it :-)
SSH-Clients (e.g. PuTTy)
It happens more and more that I need to run stuff remotely, so...
