Some awesome themes and wallpapers for the Linux Mint MATE desktop
Themes
http://gnome-look.org/content/show.php/LiNsta+3+%28Linux+is+Not+Vista%29?content=44570 Linux is not Vista. A Windows Vista styled theme for Gnome and MATE.
http://gnome-look.org/content/show.php/MacOS-X+Aqua+Theme?content=13548. Mac OSX Aqua theme for MATE.
http://gnome-look.org/content/show.php/Murrine+GTK%2B+Cairo+Engine?content=42755. Murrine GTK+ Cairo Engine.
http://gnome-look.org/content/show.php/Faenza-Cupertino?content=129008. Faenza-Cupertino icon theme.
http://gnome-look.org/content/show.php/OSX-Nostalgie?content=157390. OSX Nostalgia icon theme.
http://gnome-look.org/content/show.php/E17gtk?content=163472. E17 GTK. This is a theme for GTK that allows GTK apps to blend into an E17 desktop.
http://gnome-look.org/content/show.php/Metro+Conky?content=164107. Metro styled Conky theme. This would be an eye-catching addition to any desktop.
Wallpapers.
http://fc04.deviantart.net/fs70/f/2013/212/8/8/solaris10_hex_dark_wallpaper_by_ipodpunker-d6g38qg.png. Sun Solaris wallpaper.
UNIX commands wallpaper: http://zoreol.toile-libre.org/public/wallpaper749120.png.
Gorgeous Snowy Mountains wallpaper: http://naturespicwallpaper.com/wp-content/uploads/2014/02/Unix_wallpapers_213.jpg.
Creepy Prypyat wallpaper: http://cameronkilmister.files.wordpress.com/2013/04/cityscapes-pripyat-chernobyl-621706.jpg.
Another shot of the same location in Prypyat: http://knapo.net/photos/9/original/9-chernobyl-pripyat-%28c%29knapo.jpg.
Creepy pile of gas masks in Prypyat: http://darrenketchumphotography.files.wordpress.com/2013/08/img_5605.jpg.
A gorgeous ocean wallpaper set on another planet: http://cdn.wallwuzz.com/uploads/fantasy-solaris-sea-moon-wallpapers-array-wallwuzz-hd-wallpaper-4054.jpg.
Ubuntu logo wallpaper: http://www.ubuntuka.com/static.images/bg7.png.
Windows 8 BSOD wallpaper: http://www.geekworldnews.org/wp-content/uploads/2013/02/windows-8-blue-screen-of-death.jpg.
Commodore 64 logo wallpaper: http://darkonnia.com/download/CommodoreWallpaperHD01.jpg.
An epic planet explosion wallpaper: http://www.zastavki.com/pictures/1920×1200/2008/Space_Planet_Explosion_010521_.jpg.
Awesome giant spaceship wallpaper: http://www.upphotos.net/wp-content/uploads/2013/04/Outer-Space-Planets-Science-Fiction-Artwork.jpg.
Massive Warhammer 40K wallpaper: http://www.letstalkabout.co.uk/wp-content/uploads/2013/11/warhammer-wallpaper-08.jpg.
Misc theme links
https://numixproject.org/ Quality Numix themes.
http://www.digitalblasphemy.com/ Awesome computer generated wallpapers.
http://4walled.cc/ A wallpaper search site for the 4chan website. This will find you some awesome wallpapers.