There are prolly many many reasons why Mozilla Firefox is gaining ground like a weed on steroids, but what I love most is the CONTROL (i am a control freak!)
1: Ctrl + Number (where number is 1 - 9): this shortcut takes you to that tab, ordered from left to right. One less need for the mouse.
2: Ctrl + Tab: to open a new tab (to the right of the current tab). Ctrl + Shift + Tab opens a new tab to the left of the current tab. Nifty, ha?
3: Mouse Shortcuts: for those addicted to the now-ubiquitous rodent, some tips for you as well:
* Middle click on link (opens in new tab)
* Shift-scroll down (previous page)
* Shift-scroll up (next page)
* Ctrl-scroll up (decrease text size)
* Ctrl-scroll down (increase text size)
* Middle click on a tab (closes tab)
4: Save Webpage content: sometimes, the "save us" option does its job pretty well. Other times, some crafty webmaster "protect" the page contents - especially images. A nice work-around for this is: right-click on page (anywhere within the page, not just on the image or whatever), choose “View Page Info” then the “media” tab. Find the file you’re looking for from the list and click on “save”. Easy!
5: Delete Browsing History: When you open a new tab and type in the address bar, a drop down beneath the address bar displays all recently-visited pages. A good thing, but mostly a very bad thing!! You want to keep your favourite pr0n sites a secret? Heres how: Just drop down the URL box, scroll to the offending URL, and then press the “delete” button on your keyboard. The URL is removed from the list. Phew! A lifesaver!
6: Once every now and then, I find it a good idea to flush everything from Firefox. Just press "Ctrl + Shift + Delete", tick ALL the option boxes, click "OK". History, cookies, passwords, all gone.

more tips shall be added as i discover them...