I can help get you into a lot trouble in more ways then one

Rosie's Bakery in Boston is a good one too. They have a small store in South Station.

Here is a link:
http://www.rosiesbakery.com/

The food questions keep coming from Jenny and Friends.

Near Mikes (North End) there is another:
Modern Pastry makes a better canolli if that's what you want.

Lulu’s Bake Shoppe pretty much specializes in cupcakes and is a 1 minutes walk from Mikes (and modern). All are located on Hannover in the NE.

There's another in the NE, Bova's. The cupcakes and pastries aren't amazing, but it's actually a 24/7 shop, so if your craving hits at 2a, you can get a cupcake there.

Other neighborhoods:
Portugeuese cupcakes at O Cantinho Café in cambridge. Sorta like a flan cupcake.

South End has:
The Buttery, which makes a Cream Cheese topped cupcake.

Flour, which I think now has a waterfront location, is an organic, green, "fancy" cafe and pastry shop. The website has gorgeous food photography if you like that kind of thing (like me). My favorite for how much the chefs care about the food. Similar to SF's acclaimed ACME company.

I've got many others, but those are my favorites. Finale is very good, too, but can get loud and crowded if its the right nights. It all depends what neighborhoods you want to stick too and how far through 20 degree air you are willing to travel to feed your need.

PM if you need more info.

There is Johnny Cupcake on Newbury St and Kickass Cupcakes in Somerville. I think Johnny Cupcake is known more for their vintage T-Shirts but it will give you a sugar fix downtown....

You should also check out Flour Bakery on Washington St in the South End. Really good high end bakery and sandwiches.....

yes... flour which has locations in the south end and seaport is always good to satisfy a craving  for sweets ~ Bobby Flay recommends  the sticky buns

located south of town in Braintree     http://www.konditormeister.com    is an excellent choice

Please let me know if i can be of any more help in satisfying any of your obsessions ~ I bring my own paint-n-brush

Beard Papa at Faneiul Hall is supposed to very good for creampuffs.

on Mass Ave in Boston.  They have all sorts of nasty novelties and cakes. They are pretty good too!