Vista customization support, IE7 support, taskbar blurring, support for wallpaper management...
New in v7.x:
Native support for Windows 7, native Aero skinning, native 64-bit support (Windows Vista and Windows 7), auto-conversion of Windows XP era skins to Windows Vista or Windows 7, ability to apply textures to skins, new configuration program, clear-type support for better font handling, new skins included (Submline, Aero Metals, Corporate, Aero Woods, Aero Clay, Sabertooth, Altitude, etc.); Release Notes - Last Updated: 02.09.10 (v7.01)
New in v6.x:
“Blurred Glass” window borders on Windows XP feature (can make Windows XP look virtually identical to Windows Vista), full support for customizing Windows Vista (Internet Explorer 7 skinning, Sidebar skinning to explorer backgrounds, etc.), advanced animation support in skins, user-creatable skin sub-styles, new configuration program with user customization options of fonts and colors in skins; Release Notes - Last Updated: 03.27.09 (v6.4.100)
New in v5.01:
Improved performance on X64 based systems; support for wallpaper management; taskbar blurring; IE 7 support; various tweaks, bug fixes, and performance enhancements; Release Notes - Last Updated: 03.22.06
Pros: Offers thousands of unique skins to personalize your Windows UI, SkinStudio tool for creating your own skins from scratch
Cons: Weak search capabilities makes finding particular skins difficult, especially after you've amassed a large collection