Below are several examples of the functionality built in to this script. You can set your store to act as you please.

Example 1, when the button is clicked, adds the product to the shopping cart in real time, without any page reloads. When the customer checks out, they will see their selected products.
Sculpted Candles (10 pack)	$29.95	Quantity
Example 2, when the button is clicked shows the customer only the items they have added to their shopping cart. 1 item is automatically added.
Plain Candles (10 pack)	$14.95	Style Square Round Triangular
Example 3, when the button is clicked shows the customer the items they have added to their shopping cart as well as your other products in the same department.
Scented Candles (10 pack)	$24.95	Quantity
Example 4, when the button is clicked shows the customer only items they have added to their shopping cart as well as your entire store.
Colored Candles (10 pack)	$24.95	Quantity
Example 5, is a product not in the system. This allows you to add products to your store without even going in to the admin section. You can also add as many options as you like. Once you've created one, you simply copy and paste the code to your HTML pages to create as many as you like.
Green Jars (10 pack) Twist Top Flip Top Square Round	$14.95	Quantity
Example 6, is a product not in the system (same as example 5), but shows how you can add a select menu for the quantity field and also dynamically set the price of the product depending on the customer's selection of size.
Red Jars (10 pack)	Small $14.95 Medium $19.95 Large $24.95	Quantity 1 2 3 5 10
Example 7, shows how you can have the customer enter an amount without purchasing any products. Simply link to a department that doesn't exist. Regular text hyperlinks can also be used, but load the cart in the same window instead of a new window.