This week's keyboard shortcuts are all for Firefox - some of them may work in Internet Explorer. Recently, Microsoft have started copying features previously implemented by Mozilla in Firefox, possibly including the keyboard shortcuts. Please let me know which ones work in IE.
To cycle through your tabs rightwards: hold down Ctrl and press the Tab key.
To cycle through tabs leftwards: hold down Ctrl and Shift and press the Tab key.
To open a new tab: hold down Ctrl and press T.
To close the current tab: hold down Ctrl and press W.
To jump to the address bar - where you type in a web address: Press F6 (thanks to glytch for this one).
To open and close the Bookmarks tab: hold down Ctrl and press B (Note: if you are in a rich-text editor on a webpage this will select bold text instead.)