Summary: A list of common mistakes with e-commerce shopping cart design were identified in a previous issue of Usability News. This article revisits that list and reviews how 500 of the top Internet retail sites of today implemented their shopping cart design.

I found this part particularly amusing:

"6. (2002) Requiring a user to REGISTER before adding an item to the cart. Some sites we have tested require a user to register with personal information before an item can even be placed into the cart! This is a turn-off to users who may be browsing or comparison-shopping. They may or may not purchase the items, but they definitely do not want to commit personal information just to fill the shopping cart and will leave the site because of it.

(2007) Users still encounter this and hate it! In a recent SURL usability study of a high tech corporate website, users complained bitterly of having to register on the site before they could read a company white paper. Most said they would rather search the web for another way to access the same information rather than register with their personal information. Even requesting an email address (and not personal address info) is a deterrent.

Figure 10. Unique graphical symbols used to remove an item from the shopping cart. The minus sign (cdw.com), the ?X? symbol (simondelivers.com), and the trash can (solidsignal.com).

Read the full article from Software Usability Research Laboratory.