Someone recently posted a message about Co-Pilot - I used it for the first time today with a client and it's great. I highly recommend it!
We needed to format a letter to fit on her letterhead and I didn't have a copy of it in my office, so we were able to test print the letter and then run the mail merge on her computer.
The great part about Co-Pilot is that you don't have to pay an ongoing monthly subscription fee. You can get a day pass as you need it and pass the cost along to the client.
Here's the link:
http://www.www.copilot.com