For those designers out there looking for a little inspiration, check out Mister Retro's filters for Photoshop. One of our designers introduced this tool to me last year sometime, and I've been pretty amazed with its power.
The one I use is the Permanent Press filter, which gives the look and feel of vintage offset printing, including some super authentic halftone effects. Not to mention, the customer support is awesome.
I used really subtly recently for our birth announcement, and when printed it looked like I actually used a vintage press. Rather than having Hatch Show Print create them for me on their presses, I opted for the cheaper version. Here's how it turned out:
So be sure to check them out if you are a designer and looking for a vintage feel.