A brief description of the tools that power my classroom. This is in addition to assumed stuff like word processor and spreadsheet.
PDFPen: Edits and creates PDF files. Useful for adding images to problem sets.
LaTeX: The pretty way to typeset equations. If you've had it with Word nudging your equations in random directions, you might like this.
Adobe Illustrator: High-res vector images that don't look like garbage when printed. Great for making posters.
Pixelmator: Simple image editor that powers the red-boxed children in my photo gallery.
Dropbox: C'mon. Duh. I pay for the pro version which was kind of pricey for 100GB, but they've since made it 1TB.
Final Cut Pro X: I don't make a lot of movies, but it's necessary for our goofy class films.
Rdio: I know Spotify is the cool kid these days, but I've been a subscriber since 2011 before there were other options. And it still carries Taylor Swift. So there.
AirServer: Mimics an AppleTV on a desktop computer allowing you to display iPhone and iPad screens.
Aperture: Technically discontinued and soon to be replaced. I take my classroom photos using my phone and Aperture has hooks into iCloud putting the pictures on my home computer instantly. Less clumsy than iPhoto.
DeskScribble: Annotation on top of the desktop.
OmniGraphSketcher: Allows you to create a graph of any shape or size when you don't want to figure out the equation that's necessary. Recently open sourced.
SketchBook Pro: Primary method of delivery. I use layers like different pages.