This is a completely procedural grungy tile shader, made in Blendre using the Cycles Render Engine. The idea of going with procedural, is that everything can be adjusted! You want more cracks? No problem! Want less grunge? You got it! In this shader, I've organized all the controls, in an easy to understand format, so it's easy to quickly get the look you want :D
With approximately 200 nodes, this setup should suit your needs for just about any grungy looking tile you need.
PRO TIP: To optimize render speed, you can bake the procedural textures onto the object, after you're satisfied with it's look
If you find something which is broken, please report it to me at one of the following: