iDress for Mac

From Incarna:

iDress is a template-based solution that allows you to easily generate envelopes, Avery formatted mailing labels, custom stationery, and much more directly from your Address Book records. With iDress, you're literally only a few clicks away from your desired Address Book output. There's no need to export data. No need to mess with a convoluted mail merge process. No need to use a bloated office application. Just pick an Address Book group, pick a template, and click Go. For users who want to customize the output produced by iDress, there is an "options pallette" that provides a wide array of custom controls specific to each template category.