E-ink (non-backlit screen, more like reading on paper): Amazon Kindle, Kobo eReader, Sony Reader, Kogan, BeBook, iRiver and Cybook.
Smartphone/tablet (multi-tasking devices which run apps from most of the major ebook retailers as well as the lesser-known like Bluefire Reader and Aldiko): Apple iPad, iPhone, and iPod touch; Android smartphones and tablets eg HTC Desire, Samsung Galaxy Tab, Dell Streak, Motorola Xoom; Blackberry Playbook tablet and Blackberry smartphones; other smartphones eg Windows and Nokia.