Being a software student I have to usually make Flowcharts, DFDs and ERDs. Windows people have Office Visio as part of the Office suite for all their diagramming needs but there is no Visio in Office for Mac.
OmniGraffle is an excellent diagramming, charting, and visualization software for Mac OS X. I use this software for all my diagramming needs and find it very easy and flexible to use. Omni Group also gives educational discounts on all their software to the qualifying people through their edu-store.
While watching videos on the Internet or reading a document, it’s very annoying to have your Mac automatically dim the screen. Of course we can change that in the preferences but it’s such a hassle turning it back on or off.
Caffeine is a tiny application (240 KB) that puts an icon in the menu bar which can be clicked to prevent your Mac from automatically going to sleep, dimming the screen or starting screen savers. Clicking it again turns it off. It’s that simple!
I really like this application (for Mac) Keycue; it helps you to use the Mac OS X applications more effectively by displaying a concise table of all currently available menu shortcuts.