For health freaks out there Energy Kitchen is a place to check out. They have no items over 500 calories on their menu, but in addition they seem to have a special every month. For August 2010 they are offering $1 sides.
Now this might not sound so great, but this is a great option for a mid day snack. Their sides range from $2.99 to $4.99 and you can pull off a healthy filling meal under $3!
For the list of sides and locations check out their website!