MacStories has a very cool collection of WWDC 2014 themed wallpapers in case that's the sort of thing you enjoy. Silvia Gatta of Icons & Coffee put them together—she also did a set for WWDC 2013, and my favorite, the September 2012 Special Event wallpapers. I love my current iPhone lock screen, but the wallpaper behind my app icons might need updating. These wallpapers are available in Retina and non-Retina styles, for various dimensions of Mac displays as well as iPhones and iPads.
Check It Out: WWDC 2014 Themed Wallpapers for Mac, iPhone, and iPad