I love the Cookie Jar. Their cookie cakes are always a hit when I bring them to barbecues and they have always come through on whatever crazy decorating scheme I ask for. The cookie sandwiches are to die for (and they very well may kill you with all of their artery clogging goodness) and are one of my favorite treats whenever I'm on campus.
The regular cookies are also really good. They always seem to be ever so slightly underdone, which I love. The prices are reasonable and the staff is very friendly.
Hours are fairly limited, so call and check to make sure they're open if you plan on stopping in.