Found a collection of 3D anaglyph print ads that were created from regular images (the ones not taken with two cameras). There are plenty of companies offering the conversion service, and a few free tools; I tried Bas-relief to convert Escher's "Relativity" with, uhm, relative success. If you want to create an anaglyph image from scratch, here's a very detailed step-by-step how-to. All you need is a camera, Photoshop and a few minutes. Here's a picture of my dorm I did last night (full size):
