I am looking for some information about painting effects for the body. I am specifically looking for how to do a crackled looking paint effect. Any ideas?

1) Google (or any other search engine) for pictures of the makeup or the "finish" you would like to duplicate. 

2) Post the picture in this forum and ask MUAs (who have applied this kind of makeup successfully) which products you need to buy and possible resources for them.

3) Find a willing model and practice, practice, practice.

4) If the results suck after a number of attempts...hire a MUA experienced in body painting.

OR

5) Create the finish in post using PS.

Search specifically for Craquelure, it is a popular way of antiquing wood surfaces with a two part procedure, the paint on top drys at different rate than the primer coat resulting in cracks.  Not sure about doing it on humans but I'm sure there is a way.

It is also a filter option on PS CS as well, if and electronic version is acceptable to you.