Software for compiling approximately 30 or so photos into one a2 size photo

Hi

I'm looking to find some free, easy to use mac software in order to compile approximately 30-40 photos from facebook, which i have downloaded, into one a2 size, high quality picture for professional printing. I would like to make this as a leaving gift for a close friend who is moving back to russia in a couple of weeks, so any help would be very very very much appreciated.

Thanks a lot

Jack

Do you want to create a mosaic?
Download MozoDojo for Mac - Create mozaic tiled images. MacUpdate Mac Software Downloads
Photo Mosaic Samples | Preview A Sample Photo Mosaic | Design A Mosaic

Or just arrange them in a grid layout.
The only application that claims to do this and is free, is Picasa from Google.
Download Picasa for Mac - Organize, edit, and share your photos. MacUpdate Mac Software Downloads

You can download Photoshop as a free 30 day trial.

Posterino might make for a good choice here. Check it out.