I was playing around in Photoshop and created some chalk brushes, which I thought I'd share with you guys (see attached zip).
For them to have the desired effect, you will also have to load a pattern preset that I created for the brushes (this is also included in the zip, as well as installation instructions).
These were created in CS6, so I'm not sure how backwards compatible they are.
If there are any problems, just drop a comment!
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