Online shop - main features

General requirements:

• compatibility with PHP versions starting from 4
  
• admin backend
• flexible frontend
• final version is a complete solution for selling any products online

Design/Layout:

• template structure implementation
• fully XHTML/CSS compliant
• advanced look with AJAX technology (scriptaculous will be used)
• dynamic sections and images

Backend engine:

• ability to create/add/remove any number of products, product attributes, categories, etc.
• secure password protected administration area
• user review and user voting support 
• stock monitoring, stock comtrol
• order monitoring and control
• customer accounts management
• product listing reorganization
• secure and encrypted storage of customer personal data (MySQL server, MD5 encryption)
• simple sales reports showing top selling products in each category

Frontend:

• customizable customer accounts support
• order history and order status support for each customer
• guest account support
• temporary storage of shopping cart for guest accounts
• ability to create product review, leave feedback
• low quantity in stock warning

Additional features:

• system state monitoring
  
• promotions targeting individual customers(one to one marketing), i.e. let's say customer have bought an audio system recently and a nice idea would be to acknowledge him about new audio products, for example, CDs, HiFi, etc.
  

Possible problems:
caching, inventory upload, apache configuration, system state
 monitoring (e.g. if an error occurs system sends an acknowledgment to administrator,sounds cool, but I don't know how to make it).