Adium is like Instant Messenger and iChat but it also connects to people on Google Talk, MSN, Yahoo Messenger, Jabber and many other protocols.
Google Earth View satellite imagery, maps, terrain, 3D buildings, from galaxies in outer space to the canyons of the ocean.
DropBox provides cloud-based file storage.
Evernote is similar to OneNote.
Flip4Mac lets Apple QuickTime play Windows Media audio and video files (.wma and .wmv files)
Handbrake converts DVD format to MPEG-4 format.
Hulu Desktop Connect to Hulu shows and movies and control with your keyboard and mouse.
Jarnal is useful for notetaking, sketching, keeping a journal, making a presentation, annotating a document – including pdf – or collaborating using a stylus, mouse or keyboard. Follow instructions on the download page.
KeePass is password manager software.
Notational Velocity stores and retrieves notes.
Circus Ponies Notebook is note taking and organizing software somewhat like OneNote. Free 30-day trial, after that you pay to continue using it.
Omnifocus is task management software. Free 14-day trial, after that you pay.
Pencil is animation/drawing software. It lets you create traditional hand-drawn animation (cartoon) using both bitmap and vector graphics.
Picassa is software from Google that helps you organize, edit, and share your photos.
ProfCast is a tool for recording lectures including PowerPoint and/or Keynote slides for creating enhanced podcasts.
Skitch is a screen capture application that crops, resizes, allows sketching on the capture, and allows sharing.
Stuffit Expander extracts .zip, .rar, and .sit files. The app is essential for opening downloaded files, which are ofter compressed.
Super Duper is disk copying, backup and recovery software.
TeX allows you to typeset complex mathematical formulae.
TweetDeck connects you with your contacts across Twitter, Facebook, MySpace, LinkedIn, Foursquare, Google Buzz and more.
Wolfram CDF player allows you to view Mathematica examples, reports, and files.
Google Sketchup creates 3D models of buildings, objects, etc. Be sure to choose the Mac OS X option.
Hot Potatoes is lesson construction software that includes six applications, enabling you to create interactive multiple-choice, short-answer, jumbled-sentence, crossword, matching/ordering and gap-fill exercises for the World Wide Web. Your actvities can be added to Moodle, where student progress can be tracked.
Growly Notes is very similar to OneNote
Jing lets you take a picture or make a short video of what you see on your computer monitor. Save or share it instantly via web, email, IM, Twitter or your blog.
Kindle Reader Install this to read Amazon Kindle e-books on your Mac. No Kindle required.
Nook Reader Install this to read Barnes &Noble e-books on your Mac. This is a beta version.
Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file.
VLC is a free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVD, Audio CD, VCD, and various streaming protocols.