General
Win+Up Maximize
Win+Down Restore / Minimize
Win+Left Snap to left
Win+Right Snap to right
Win+Shift+Left Jump to left monitor
Win+Shift+Right Jump to right monitor
Win+Home Minimize / Restore all other windows
Win+T Focus the first taskbar entry
Pressing again will cycle through them, you can can arrow around.
Win+Shift+T cycles backwards.
Win+Space Peek at the desktop
Win+G Bring gadgets to the top of the Z-order
Win+P External display options (mirror, extend desktop, etc)
Win+X Mobility Center (same as Vista, but still handy!)
Win+#
(# = a number key) Launches a new instance of the application in the Nth slot on the taskbar.
Example: Win+1 launches first pinned app, Win+2 launches second, etc.
Win + +
Win + - (plus or minus key) Zoom in or out.

Explorer
Alt+P Show/hide Preview Pane

Taskbar modifiers
Shift + Click on icon Open a new instance
Middle click on icon Open a new instance
Ctrl + Shift + Click on icon Open a new instance with Admin privileges
Shift + Right-click on icon Show window menu (Restore / Minimize / Move / etc)
Note: Normally you can just right-click on the window thumbnail to get this menu
Shift + Right-click on grouped icon Menu with Restore All / Minimize All / Close All, etc.
Ctrl + Click on grouped icon Cycle between the windows (or tabs) in the group