Since retro/vintage style is a trend, here are some great links for inspiration.

Found in Mom’s Basement
50 Inspiring Vintage Advertisements
Retro and Vintage In Modern Web Design
Celebration Of Vintage and Retro Design
Vintage and Retro Typography Showcase
Retrolounge

Free retro/vintage resources:

300+ Vintage Style Textures and Photoshop Brushes
Grunge retro car vector illustration
Vintage Mega Pack 4 free samples
Vector Pack: Tres
Vintage Music
Vintage 3D [...]