Taskbar on each monitor:
Start menu
notification area a.k.a. system tray
clock
Jump Lists support under Windows 7
Pin to Taskbar
grouping similar buttons
preview thumbnails (with the Aero Peek feature under Windows 7)
progress bars on taskbar buttons under Windows 7
Show Desktop button under Windows 7
Quick Launch and other toolbars
dragging the taskbar buttons with the mouse on systems before Windows 7
dragging the system tray icons with the mouse on systems before Windows 7
semi-transparent taskbars on systems before Windows 7
native look in any visual theme - from Windows Classic to Windows 7 Aero

Alt-Tab Task Switcher window on each monitor:
new window controls specially designed for a work with multiple monitors
additional button in each window's title bar to put a window instantly to any monitor
additional button in each window's title bar to maximize a window to entire desktop
special hotkeys to put a window instantly to the next/previous monitor
automatic placement of windows by default to the monitor which the mouse pointer is on
automatic placement of certain windows to the specified monitors
easy dragging/sizing of windows - by clicking anywhere inside a window
snapping a dragged/sized window to desktop boundaries and other windows ("sticky borders")
emulation of Windows 7 Aero Snap on Windows XP/Vista
single-click maximization of windows - to entire desktop, to monitor's width, to monitor's height
custom wallpaper - single on entire desktop or in!-->!idual per monitor (with the ability to run a background slideshow)
custom screen saver - single on entire desktop or in!-->!idual per monitor
custom desktop profiles - switch between various desktop configuration in a flash!
keeping the order of desktop icons after the desktop configuration/resolution has been changed
desktop mirroring - observe various parts of desktop (windows, monitors, arbitrary areas) in separate floating windows called mirrors.