Originally Posted by http://www.craftbits.com/viewProject.do?projectID=571

Make a cup of tea with a tea bag and let the bag steep for five to ten minutes. Let it cool down and remove the bag. Gently squeeze the tea bag to get rid of any excess water. Then use the tea bag as a sponge to dab the stain onto your paper.

Alternatively make a cup of strong instant coffee and let it cool down. Paint your paper with the cooled coffee with a paint brush or sponge brush.

Depending on how strong your coffee is will determine how deep of a stain you achieve.