I set up the postcards in MS Word (landscape, 4-cell table) and then take them to Kinko's to print and cut. MS Word mail merge for labels, print them on clear labels and drop them off at the post office!
I did my business cards in MS Word as well and took them to OfficeMax where they put them 10-up, copied them, and printed them for me.
I found this absolutely PERFECT 80# gray marble paper that I use for mailings and business cards and the matching 24# paper for stationary and envelopes. - After all, shouldn't a Goddess be on a marble background?