Except for the Hogwarts castle ride, you will notice most of the lines in the Harry Potter World at Universal Studios are simply to get into the shops.
I'm not really sure why everyone wants to stand in line for the shops; maybe it's for the atmosphere or ambiance inside the store...
or maybe they just don't know the secret to get around waiting in line.
When we were there in March 2011, my daughter and I went into the Honeydukes candy shop and Zonkos magic tricks shop (the two stores are joined together with a single line to get in).
The line moved really quick; it took only about 5 minutes with around 20 people ahead of us.
Honeydukes was like most typical stores inside, except it had lots of candies and tricks on the shelves.
The only truly unique thing about this particular store was they had "ear" phones hanging from the ceiling (like the ear on a string used in one of the Harry Potter movies).
By the way, when you see people coming out of a door where there is no line, it's because that's an "Exit Only" door.
However, the cool thing we discovered is you can get most of the really popular Harry Potter products without waiting in line.
If you want to spend hours waiting in line to get into all the little stores in the Wizarding World portion of Universal Studios, go ahead...
enjoy the ambiance once you get inside.
However, if you would rather enjoy the town and the rides...
without having to wear or carry around stuff you buy in the on-site shops...
and wait until you are about to leave the park, you can stop at the gift store just inside the entrance to Universal Islands of Adventure.
This gift store has almost the full selection of wizarding world products at the same prices...
but without the wait! Here's a list of genuine Harry Potter products you can get at this gift store: • Harry Potter Wands • Cloaks from each of the 4 houses • A variety of Harry Potter T-Shirts and sweatshirts • Chocolate Frogs • Other candies from Honeydukes (e.
g.
, Peppermint Frogs, Imps {cinnamon hard candy}, Every Flavor Beans, etc.
) • Keychains • Remembrals • Brooms • Journals from each of the four houses (Griffindor, Ravenclaw, Slytherin, & Hufflepuff) • Scarves from each of the four houses • Ties from the four houses • Marauder's Maps • Caps • Quill Pens (like the one that scratches blood in Harry's hand) • Rita Skeeter's Pad & Quill • Quidditch items such as the quaffle balls, bludgers, and the snitch • Hedweg puppets (that's Harry's owl) • Pygmy puffs (cute, pink fluffballs with eyes, nose, and mouth) • Stuffed rats (Ron's pet "Scabbers") • Stuffed Persian cats (Hermione's pet "Crookshanks") • Dragons (both figurines and stuffed) • Time Turners • And lots more!!!  By the way, if you get one of the hotel packages associated with Universal Studios, you will also receive a 15% discount card for food, drinks, and merchandise, but it is not accepted for Harry Potter products.
You also can't use the 15% discount card for food and drinks at any of the carts.
A "cart" is any place that is not inside a real building sells this stuff.
Fortunately, there are other completely legitimate ways Universal Studios will give you discount prices on all this stuff.
So, why wait in line to get all your Harry Potter souvenirs and paraphernalia.
Just shop at the gift stores near the entrance on the way out, and then you won't have to carry stuff around all day.