This DIY from Techlife instructs you on how to create one of those cool collage "Life Posters" using only the free web program Picasa. This is a cool way to display similarly themed images unworthy of large solo prints. Showcasing a set of images from your current vacations becomes less tedious, both to create and view (and your friends will be happy they don’t have to sit through another two hour slideshow).
You can also use this technique with camera phone images. Most images from phones are far too low of a resolution to do anything with except create avatars or use as backgrounds on your phone. Using this technique, you can gather a bunch of images from your phone (or many phones over the years) and compile them together into a very printable poster that you can hang.
Image: flickr user mrlerone via CC