Mark (and others too, if you find this useful):
I recently found a proofing easel on eB**, which makes it easy to put four 4x5 prints on one 8x10 sheet, so for my the last two exchanges I've sent out 4x5 cards.
Prior to using the proofing easel, I was printing two 5x7s on one 8x10 sheet. I use a four blade easel, so I needed to tape masks in the appropriate places on the easel for this to work.
I like the larger cards, and the postage (in Canada) is the same, so I might go back to them.
I try to use a negative that I don't have to split grade.
For the labels, I use the mail merge functions in my word processing software (WordPerfect). I use that function for lots of different things, so it isn't that difficult for me to use the search and replace functions in that software to re-format the comma delimited list into a data file suitable for the merge.
The first attachment is the form file I used for the last exchange. I used it to print three small labels (Avery 5160) for each card.
The second attachment is the data file I used with just one example address shown - that of our fearless leader, Sean (whose mailing address has been posted publically in these threads).
The attachments have been pdf'd - if you don't use WordPerfect they may not be in the same in format as you would use. In addition, I've modified the data file slightly to make it more visible (by taking out the page breaks).
Hope this helps.
P.S. I try to add at least a handwritten signature, if not a short handwritten note as well.