Sure...
"Best Program Ever" is a pretty big call. But I'm sure you will agree this lives up to the claim. Want to print a life sized picture of your favourite gal? Worried that if you do, you might end up with pixels the size of bowling balls? I have the solution for you!
Introducing the completely free (and suggestively named) Rasterbator:
http://homokaasu.org/rasterbator/
It's available as a web service (FREE) or as a tiny (less than 1Mb) standalone download (which is also FREE)!
It takes a bitmap picture (jpeg, gif etc.), and turns it into a pdf that can be printed at any size. You can control the detail, page size etc. It's absolutely amazing. If you have a little A4 inkjet, you can tell the program to split it up over say 20 pages and you can stick them together to make one enormous image. Check out the sample gallery on the site to see what I mean:
This is not me before you all ask....
How huge is this image?
If you look closely, this is made up of about 30 or 40 pieces of paper.
Luckily I have access to a 60" HP Designjet printer at work. Hmmm.... lifesize Dayanna or Uma anyone? Try it out yourselves and let me know how you go with it.