Here are some of the new features in Windows 7.

Windows Explorer
You can now organize your folders virtually by using Libraries. Files can be copied between these virtual folders and the corresponding folders will be updated. To create new libraries all you have to do is right click the folder you want to add and chose Include In Library.

Pinning applications
You can now pin applications to the task bar (quick launch).

Aero Peek
If you click a button on your task bar and hover over the open application the background will become transparent and you can see the application hovered.

Minimize all applications
You now have the option to minimize all applications by clicking the small bar next to the clock. Many consider this a feature similar to the "Boss Button".

Aero Snap
You can now drag windows to the top of your screen and they will automatically maximize. If you drag the application to either left or right side of the screen the application will maximize to half the screen size.

Aero Shake
If you click and "Shake" one of the open windows, all other open windows will minimize.

New Shortcuts
Windows key + Space bar operates as a keyboard shortcut for Aero Peek.
Windows key + Up maximizes the current window.
Windows key + Down if current window is maximized, restores it; otherwise minimizes current window.
Windows key + Shift + Up maximizes the current window, in the vertical direction only.
Windows key + Left snaps the current window to the left edge of the screen.
Windows key + Right snaps the current window to the right half of the screen.
Windows key + Shift + Left and Windows key + Shift + Right move the current window to the left or right display.
Windows key + + (plus sign) functions as zoom in command wherever applicable.
Windows key + − (minus sign) functions as zoom out command wherever applicable.
Windows key + ESC (Escape key) turn off zoom once enabled.
Windows key + Home operates as a keyboard shortcut for Aero Shake.
Windows key + P shows an "external display options" selector that gives the user the choice of showing the desktop on only the computer's screen, only the external display, with the same output on both (clone), or on both displays with independent desktops (extend).

Taskbar Shortcuts
Shift + Click, or Middle click starts a new instance of the application, regardless of whether it's already running.
Ctrl + Shift + Click starts a new instance with Administrator privileges; by default, a User Account Control prompt will be displayed.
Shift + Right-click shows the classic Window menu (Restore / Minimize / Move / etc.); right-clicking on the application's thumbnail image will also show this menu. If the icon being clicked on is a grouped icon, the classic menu with Restore All / Minimize All / Close All menu is shown.
Ctrl + Click on a grouped icon cycles between the windows (or tabs) in the group.