Jumsoft makes all sorts of apps and and adds on to Keynote, Aperture, Numbers and web templates. They've offered a nice sampling of goodies for free, and I like their holiday card mail templates designed as Apple Mail stationery.
I think most users never check the stationery feature, either because they don't know it exists, or because they find the templates tacky or not relevant.
If you've never seen the templates at all, open Apple Mail, create a new message, then click on stationery in the upper right of the message window and you'll see the default catalog.
Jumsoft provides some tasteful and graphically dynamic holiday cards that are certainly worth exploring. They also offer a paid set of mail stationery that covers just about anything, and are the best I've seen offered.
It might be worthwhile to explore the Jumsoft goodies page. There are free downloads for Keynote objects, iWeb, Freeway and RapidWeaver themes, and some polished themes for Keynote. They are all samples of larger sets that Jumsoft sells, and a great introduction to the quality of their work.
And do get those greeting cards out before the 26th!
Thanks to Dick for the tip on the freebies.