I have to disagree about Toni Marie's. Although there cakes are stunningly beautiful, I have yet to taste anything that is above average. You'd do better off going to Omega Restaurant in Downers and grabbing something off of their bakery shelves.
The Upper Crust bakery in downtown Lisle by the traintracks is fantastic. Can be a little pricey, but everything is incredible. They always have a ton to choose from. Owner is Polish and the polackys are the best we've ever had.
Kirschbaum's Bakery in Western Springs is an older bakery that is supposed to be very good...I have not been there, but one of my co-workers who's from Hinsdale speaks highly of it. It's located right near the train tracks on Burlington near the Casey's in WS.