It pays to be polite and these cute retro martini thank you cards make it even better. They're sold individually (one card, one envelope) on MartiniArt.com for $0.75 each. The site is also worth checking out for it's great cocktail and appetizer recipes!
Charles and Ray Eames are the superstars of mid-century modern furniture design and now you can get a hardbacked journal featuring some of their classic pieces. You can buy it from Amazon.com for $9.99, or, if you're looking for something more fun, there's an Eames Stamp Kit with 21 rubber stamps of Eames designs.