Easy Retro Picture Effects
Cross Processing Effect (Super Easy)
Retro Text Effect
Retro Poster Tutorial
Retro Curves With A Modern Twist Tutorial
Retro Poster Tutorial
Advanced Retro Gig Poster Tutorial (Advanced, but sweet!)
Super Vintage Photographs
Vintage Dreamy Effect Tutorial (Love it!)
Retro Inspired Poster (Not quite retro, but inspired by the times!)
Also, check out these awesome free retro resources!
Fonts
Groovy Fonts via dafont
Old School Fonts via dafont
Retro Fonts via dafont
Retro Fonts via 1001FreeFonts
40 Free Fonts Ideal For Retro And Vintage Designs via bluefaqs
Brushes
500+ Free Retro Photoshop Brushes
Retro Inspiration
Note: Pay attention to the color schemes in most of these 'retro' images and you will notice they are mostly the same. This will give you an idea of the colors your retro designs should aim towards).
Tons of Retro Movie Posters
Celebration of Vintage and Retro Designs (An enormous variety of retro graphic design and original retro posters and advertisements).
50 Retro Inspired Photoshop Inspirations
40 Vintage and Retro (mostly vintage) advertisements
Have some more inspiring, useful, or awesome retro resources? Let us know in a comment below!