mozilla firefox and gmail shortcuts
Ctrl + Tab or Ctrl + PageDown: Cycle through tabs.
Ctrl + Shift + Tab or Ctrl + PageUp: Cycle through tabs in reverse.
Ctrl + (1-9): Switch to tab corresponding to number.
Ctrl + N: New window.
Ctrl + T: New tab.
Ctrl + L or Alt + D or F6: Switch focus to location bar.
Ctrl + Enter: Open location in new tab.
Shift + Enter: Open location in new window.
Ctrl + K or Ctrl + E: Switch focus to search bar.
Ctrl + O: Open a local file.
Ctrl + W: Close tab, or window if there's only one tab open.
Ctrl + Shift + W: Close window.
Ctrl + S: Save page as a local file.
Ctrl + P: Print page.
Ctrl + F or F3: Open find toolbar.
Ctrl + G or F3: Find next...
Ctrl + Shift + G or Shift + F3: Find previous...
Ctrl + B or Ctrl + I: Open Bookmarks sidebar.
Ctrl + H: Open History sidebar.
Escape: Stop loading page.
Ctrl + R or F5: Reload current page.
Ctrl + Shift + R or Ctrl + F5: Reload current page; bypass cache.
Ctrl + U: View page source.
Ctrl + D: Bookmark current page.
Ctrl + NumpadPlus or Ctrl + Equals (+/=): Increase text size.
Ctrl + NumpadMinus or Ctrl + Minus: Decrease text size.
Ctrl + Numpad0 or Ctrl + 0: Set text size to default.
Alt + Left or Backspace: Back.
Alt + Right or Shift + Backspace: Forward.
Alt + Home: Open home page.
Ctrl + M: Open new message in integrated mail client.
Ctrl + J: Open Downloads dialog.
F6: Switch to next frame. You must have selected something on the page already, e.g. by use of Tab.
Shift + F6: Switch to previous frame.
Apostrophe ('): Find link as you type.
Slash (/): Find text as you type.
Note: Must have "keyboard shortcuts" on in settings.
C: Compose new message.
Shift + C: Open new window to compose new message.
Slash (/): Switch focus to search box.
K: Switch focus to the next most recent email. Enter or "O" opens focused email.
J: Switch focus to the next oldest email.
N: Switch focus to the next message in the "conversation." Enter or "O" expands/collapses messages.
P: Switch focus to the previous message.
U: Takes you back to the inbox and checks for new mail.
Y: Various actions depending on current view:
Has no effect in "Sent" and "All Mail" views.
Inbox: Archive email or message.
Starred: Unstar email or message.
Spam: Unmark as spam and move back to "Inbox."
Trash: Move back to "Inbox."
Any label: Remove the label.
X: "Check" an email. Various actions can be performed against all checked emails.
S: "Star" an email. Identical to the more familiar term, "flagging."
R: Reply to the email.
A: Reply to all recipients of the email.
F: Forward an email.
Shift + R: Reply to the email in a new window.
Shift + A: Reply to all recipients of the email in a new window.
Shift + F: Forward an email in a new window.
Shift + 1 (!): Mark an email as spam and remove it from the inbox.
G then I: Switch to "Inbox" view.
G then S: Switch to "Starred" view.
G then A: Switch to "All Mail" view.
G then C: Switch to "Contacts" view.
G then S: Switch to "Drafts" view.