Things to remember when you are online shopping are as follows:
Can I get this at the mall? If so then why are you paying for shipping. However there are SO many things that you can't find locally it can make sense to order it.
Remember to factor in duties, foreign exchange and shipping. When our dollar was on par with the US I was a JCrew fanatic, now I think twice before I order.
Can you wait for a sale or free shipping promotions? Sometimes it pays to wait, online boutiques often have some sort of promotion!
More than ever people are online window shopping, comparing prices before heading out to the bricks and mortar location of their choice.
For stores that you can actually drive around the corner to or even destination shop, online shopping doesn't really make sense. But it does make sense to plan out your trip before you go. Online shopping can also tide you over between shopping excursions!
Take note however, many online boutiques or web versions of national chains don't necessarily have everything in store on their website OR their website includes more than you will find at your favourite location.
What does that mean? Know your favourite stores and what to expect so that you aren't disappointed.

Anthpologie - before our first Toronto location opened, I had already planned out what I was going to buy!
The website is extensive however and includes swimsuits and shoes that I have yet to see at the bricks and mortar location.
These could be online only products OR these could be US only products.
Nevertheless if you are craving a pair of shoes from Anthropologie you will have to order online. They do ship to Canada!

Gap, Banana Republic & Old Navy - Gap et al doesn't ship to Cananda(not YET), which isn't that big of a disappointment as most cities, even smaller cities now have at least a Gap at the mall.
The website is a great way to research what is in store and plan a trip if there is something you like!

Danier Leather - Danier has a great site which has all the
leather jackets, coats and blazers you would ever need at your finger
tips!

Roots - Roots makes truly
beautiful leather bags and their latest brightly coloured selection is
fantastic.
Roots is also my go to retailer for hoodies. Another perk of the online store is the large selection of kids and baby which many Roots locations do not include.
It can be worth it to shop online for Roots - if you spend more than $100 shipping is free. Who needs the mall anyways?

Toys R Us - Toys R Us and Babies R Us websites are fantastic and extensive.
You can create a registry and manage it from your home and find out which location has what you are looking for in stock.
If you need to they ship across Canada and often have free shipping promotions.
These are shops I have ordered from or order from regularly. They are torontoShopoholic reccomended!

JCrew - the quintessential American catalog has been an online retailer for as long as I can remember.
They ship to Canada and have an excellent sale section. Check out their wedding and bridesmaids selection - top notch.
I personally frequent JCrew for their shoes, cashmere and cords! I have found that shoes run true to size, where as other items can run a bit small.

Revolve clothing - Revolve clothing carries all your contemporary designer favourites, high end jean lines and great shoes and accessories.
From Diane Von Furstenburg to Tibi, Micheal Stars and Frye boots this website is an excellent tool to watch trends and buy that Kooba bag you have seen worn by the stars!
Check out the product reviews you will find whether the item you are looking at runs true to size or if you have to order up or down!

Sephora - Sephora's online store is immense! You can find all your favourite professional beauty products and more online.
Watch for items that do not ship to Canada, which can lead to disappointment.
Granted you can get many products in store, I have found that the online store carries many times what the bricks and mortar locations do, especially for lesser known brands.
For example, while the Toronto locations do carry Korres products, the Sephora website carries their full product offering plus Sephora only selections!

Bluefly - Bluefly is a designer discount retailer. Many of the brands you find here are contemporary designer fashions like those at Revolve Clothing.
However these are discounted!
Granted they aren't necessarily this seasons, but you can get a Gucci bag for less than full price!
Watch out however, Bluefly uses DHL for shipping which makes it harder to pick your package if they "deliver" when you are not at home.
You can not go to your local postal outlet and sign for it, you will be sent to a DHL location which may not be convenient.

Overstock - I found Overstock.com a few years ago when looking for a gift, and was disappointed when they didn't ship to Canada.
This has all changed however and Overstock is adding new international locations to their shipping all the time!
This site is EXCELLENT to find discounted items from clothing, shoes and accessories, to home and electronics. Online shopping at its best.
Make sure you like what you are ordering as they charge a return fee.

Zappos - the online shoe retailer you will often see featured on What not to Wear ships to Cananda, in fact theyhave a Canada specific website. Zappos has a multitude of shoes at many price points, wide widths, cowboy boots. They pretty much carry it all.

Etsy - Etsy is a website which houses online stores for artists, sewers, crafty people to sell their wares. If you are looking for something truly one of a kind, look here. There is jewelery, clothing, fabric, soaps, you name it!
Happy online shopping!