Google Reader:

Useful keyboard shortcuts:

• j/k: next/previous item
• space/<Shift> + space: next/previous item or page
• n/p: scan down/up (list only)
• o/enter: expand/collapse (list only)
• s: star item
• <Shift> + s: share item
• v: view original
• t: tag item
• m: mark item as read
• r: refresh
• u: toggle full screen mode
• <Shift> + a: mark all as read
• 1: switch to expanded view
• 2: switch to list view
• <Shift> + n/p: next/previous subscription
• <Shift> + x: expand folder
• <Shift> + o: open subscription or folder
• g then h: go home
• g then a: go to all items
• g then s: go to starred items
• g then t: open tag selector
• g then u: open subscription selector