I love the idea of filling walls with oversize photos from family or travel albums. The Dutch brand, ixxi, makes it super easy. Through their website, you can upload your own photos (or grab some art from their image bank) to create oversize images for your walls. They will send you the image (divided up into little cards) which you can then attach using their x and i modular connecting system. They also have a system for giant photo collages and wall dividers. Here are some of my favorite uses of their product.
Images courtesy of ixxi.