I Have personally worked on lots of commerical projects involving :
Secured web development:
Setting up shopping carts, Showcasing Products, Managing Payments, Creating Modules for payments, Site layout, Site CMS Development
Database design and administration:
Normalising the site database, monitoring the ongoing activities within the database, Maintaining the database structure, Archiving older entries, Managing Backups and restores
Hardware interfacing:
Interfacing Mobile Phones, Memory Card Reader Writers, Credit Card reader writers with the computer
Graphical User Interfaces and Design:
User interface design for the websites and application softwares
Compilers
Integrating Verilog VHDL compiler with an application softwares to be ported on Embedded Devices