For Espresso lovers in the OC, I wanted to bring your attention to this little independent in Orange. They really do an excellent job with espresso. All of their espresso orders are doubles (which only makes sense really!) and when I ordered a machiatto, it was absolutely perfect, just "marked" by a bit of steamed milk. The crema was very good, and the flavor was dark, deep and round exactly the way great espresso should be. They do not roast their own in-house but supposedly the owner is very particular (and a little secretive) about his source for beans.
They also have a row of panini presses, and seem to do good business with them around lunchtime. I only had the espresso so I cannot say how they were, but they looked good. Kaffa! also has the usual coffeehouse fare like muffins, pastries etc.