As you exit through the back of the Leaky Cauldron into Diagon Alley, a flood of busy sights, sounds, and smells meets you. Numerous shops line a narrow street and there are plenty of busy shoppers going about their business.
First on your left is a small cauldron shop, the sign is partly covered by ivy, but it should say "Carrington's".* Just outside a column of cauldrons hold up a sign that reads, "Cauldrons/ All sizes/ Copper, Brass, Pewter, Silver/ Self-Stirring/ Collapsible". Inside, you can see the merchandise stacked up to the ceiling. A couple shops down, to your right is Slug & Jiggers Apothecary. Outside the shop, there are barrels of standard unperishable potion ingredients, labeled with prices per pound. There seems to be an unfamiliar mix of smells from inside, making you wary of going in. But through the window you can see fascinating things hanging from the ceiling, and far on the back wall, a shelf of all the rarest prizes from wild beasts. Two doors down, Quidditch Quality Supplies displays the newest brooms and full sets of professional robes in its windows. Next door, Inks 'n' Things -Stationary Shop* sells parchments and seals, as well as quills and specialty ink. Immediately across the way, Eeylop's Owl Emporium displays a sign advertising the sale of "Tawny, Screech, Barn, Brown, and Snowy Owls" and supplies. Between Eeylops and Madam Primpernelle's Shop, a tiny Magical Instruments shop seems to be hiding. Madam Pimpernelle's Beautifying Potions headquarters is located at number 275. The company creates potions and magical kits to help Witches remove "warts and worse". Across the Alley, Flourish & Blott's is a two story Wizarding Bookstore. Large front windows display the newest shipments and past them, all you can see is bookshelf after bookshelf filled with texts in every subject. Next door, Madam Malkin sells Robes for All Occasions. She is a stout witch herself, and on busy days you can see her ordering around several assistants. Some of her finest dress robes are hung along the walls with a sign that says "Fingers to yourself, Please." From Madam Malkin's, you can see the vintage patio tables and chairs of Florean Fortesque's Ice Cream Parlour.The old man serves only the finest variety of magical flavors, with a fair selection of toppings.
Just before Diagon Alley turns into Knockturn Alley, Twilfit & Tattings sells high quality robes and wizarding accessories. At the corner stands an unusually large white building. Engraved upon the front, it reads, "Gringrotts Bank." Through the entrance, there lies a large marbled lobby. A series of desks seat golbins, who ultimately run the wizarding bank. You can open an account, exchange Muggle money, or deposit and withdraw from one of the banks many underground vaults [if it's yours!]. The goblins are very confident of their security system, and if you find yourself greedy, watch out for dragons.
Down Diagon Alley, on the same side of Madam Malkin's, the Magical Menagerie is hard to miss. Cages large and small fill the shop. From the looks of it, they may very well sell any animal you'd take a liking to, as well as food and supplies. Right next door to the Menagerie is no quieter a place. Gambol & Japes sells a number of jokes, tricks, and treats. But hidden nearby is a tiny second hand robe shop for those with a budget. Tucked in nearby lies Ollivander's with a sign that says "Makers of Fine Wands Since382 B.C." There is a single wand on a violet cushion in the window. It may seem like a small shop to the customer, as piles and rows of wands in boxes line the walls. Airy and bright [and a little frieghtening] Mr. Ollivander remembers every wand ever sold to every customer. Across the street, the Daily Prophet headquarters and offices houses the making of the newpaper. And a couple doors down, a large junk shop entitled "All You Can Imagine" is filled floor to ceiling with... junk. And right next door lies number 93 of Diagon Alley, a large shop currently for sale itself, but no one has looked in it for years.
* Name made up by me. :3 All other info from teh HP Lexicon