We're laying brick next to a 10x10 concrete slab. Is there some sort of paint/stain that can be put onto the concrete to make it look closer in color to the brick? Is it possible to create patterns?

There are tons of stains on the net and at the box stores Kemiko Stone Tone Concrete Floor Stain (http://www.kemiko.com/) If the concrete were fresh the stain is actually a powder, cured concrete takes a acid stain. You can creart patterns but it is much more labor intensive.