Tornby is a suburb in the north of Linköping. I've found it to be a great place to do some shopping, not just for clothes, but for furniture, books, computer equipment...
There are about 3 main shopping buildings here, all within 5 mins walk of each other. The main building is IKANO huset and IKEA. IKEA speaks for itself, cheap and good items that can furnish or decorate any part of your home.
IKANO is like a shopping mall. There are some restaurants, a lot of clothing stores for men and women (Vero Moda, Jack & Jones, H&M, Wedins, MQ, Lindex, Intersport, Åhlens, Brothers, Sisters), stores for homeware (Duka and Hemtex), phone stores (Telia, Telenor, 3 and The Phone House) as well as a supermarket, chemist (Apoteket), newsagents and bookstore.
The next building across from IKANO huset has a Toys R' Us, El-Giganten (electronics and white goods store), Skopunkten (shoe store - men, women and children) and a large Stadium (sportswear) store.
The next building over (called JULA huset) has Europris, a Max fast food restaurant and PC City. PC City is a really good place to buy anything to do with computers (it's where I bought this laptop I'm writing on now!), and the staff there are very helpful in trying to verify what is going to suit you best.
Also shops in the area are (generally) open at:
(Buses run frequently in this area, and there are a lot of car parks available)
What to buy: IKEA is always a good place to look at. And Stadium as well (although sometimes the prices are a bit expensive).
What to buy:
Within a walking distance from the cathedral is Linkoping town center.
Easily accessible, with pleasant squares and pedestrian streets here can be found major chain stores (H&M), trendy boutiques or specialist shops.