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This is another blog post for digital artists pretty much exclusively.
Recently while learning about procedural texturing I saw an interesting use of Ambient Occlusion. The point was made that objects tend to develop rust and grime in areas that are partly, or completely occluded.
Since adding rust and grime is a big part of adding realism to textures, I set out to find ways to apply this to traditional texturing.

The basic process is to first adjust the curves of your AO map so there is little grey, you don't want the rust/grime fading in and blending with the base color, you want it to appear to be on top.

Once you've got that looking nice, Use the adjusted map as a layer mask. (To paste the map directly in, you have to ALT-click on the layer mask to open it in 'document mode', then ALT-Click again to get back to your regular project.)
Here's the AO map, and the resulting texture from this process.

Clearly this is far from completed, but it's a quick and easy way to lay in some detail in the right areas. Obviously you'll need to go in and do some brush work to make it look more realistic. Adding some noise to break up the AO map (render clouds set to overlay...) is one possible solution. I think this could be very usefull if you needed to texture a lot of background props very quickly. I'd be hesitant to use this method on a main prop, unless it was just to block in the details in a first pass.

If you're a 3D artist and you want to work on Current/Next gen games, normal mapping is an incredibly important skill to know. If you're visiting mt blog and you're not a 3d artist, this may be a post to skip, unless you're looking to educate yourself on deeply geeky topics. To fill you in, a normal map adds additional shading information to the surface of an object, to make a simple shape look more detailed usually.

I recently had a friend who was working for Infinity Ward look over some of my project files, and he pointed out some causes for normal map errors I was facing. Basically he told me that wherever you have a hard edge on your model, you also need to separate those areas in your UV map. This is caused by Ray misses in the projection from the Low to Hi poly model.

I put together some simple test renders so that I could wrap my head around the concept more. Here they are, with a screen cap from Maya first for reference.

Example 1

Example 3

Don't turn it off.
Instead, go to View>Pixel Aspect Ratio>Square

If you've done a lot of 3d rending you've probably come up against the error before. More than likely it's because you picked a preset that doesn't default to square pixels. Not to fear, you are saved.