#1Resizing the dock: Move your mouse hover the stripes that are separating your dock apps and the trash and click on it and start resizing your dock.
#2 Controlling the dock with your keyboard: Press Control + fn + F3; then move within the dock with your arrow keys : Left and Right to navigate through the apps, Up to view app controls
#3 Indicator Light: In Lion, this feature is disabled by default. To enable it go to System preferences > Dock > Mark 'Show indicator light for open applications'
#4 Resizing windows: To resize windows hover your cursor over any window edge
#5 Mission Control: Press F3 for Mission control to pop up..Alternatively,you can swipe three fingers upward.
#6 Swiping between Fullscreen Mode(s): Swipe three fingers to the left/right to navigate through Fullscreen mode..You can add Fullscreen modes in Mission control
#7 Safari gestures: Swipe two fingers on the trackpad (left/right) to navigate through webpages
#8 Accented characters: Hold down a key and a little box with accented characters will pop up. Note: this only works with letters: a,e,i,o,,u
#9 White on Black: Hold Command,Control,Option and 8 for some fun.
#10 Spotlight shortcut: Command + Space Tip: Hover over any file and a little window with all the information will appear.
#11 Cursor size: You can resize your cursor by going to System preferences > Universal access > Cursor size
#12 Taking screenshots: To take a screenshot on your Mac press Command,Shift and 3. The screenshot will be then automatically saved on your desktop