Mozilla introduced Firefox 3 Beta 5 on Wednesday, with more than 750 changes from the previous beta, including improved stability and Web compatibility, user interface enhancements, performance improvements, and better integration with Windows, the Mac, and Linux.Get it at the Firefox 3 beta home page.

Mozilla says the beta is only for testing purposes, but I've been using Firefox 3 betas as my primary browser since December, and they work fine.

My favorite new feature of Firefox 3 is the way it turns the address bar into a control center for your bookmarks and history. When you want to visit a page, just go to the address bar and start typing. Firefox automatically throws up suggestions as you type, digging the URLs out of your bookmarks and history and learning what URLs you want by remembering your browsing habits.

This is what it looks like when I type the first three letters of the name of this site into the address bar:

This awesome robot lives on the What's New page for the Firefox 3 Beta.

As you type, you'll see a drop-down of all the sites in your history or bookmarks that match what you're typing. The drop-down is rated for "frecency," a made-up word Mozilla uses to describe its algorithm that weights URLs by the frequency you visit, and how recently you visit.

Notice the star next to the second URL in the dropdown: That indicates that the URL is in my bookmarks database. The icon on the next entry, which looks like a little price tag, also indicates that the URL is in my bookmarks database, and that it's tagged with a keyword that starts with "inf". (The full keyword is, of course, "informationweek.")

The only problem with the new beta that I can see so far is that it breaks two of my favorite Firefox extensions: Adblock Plus and ScrapBook, which worked in Beta 4. And two other favorite extensions of mine have never worked in any of the FF3 betas: del.icio.us bookmarks, and TabMix Plus.

To learn more about Firefox 3, read our review of Beta 1, which covers pretty much all the features: Review: Firefox 3 Beta 1 -- Packed With New Features And Rock Solid. And if you want more, see Review: Firefox 3 Beta 2 Continues Bookmarking, History Improvements, and Mozilla Introduces Firefox 3 Beta 4.

And Lifehacker has more details of what's in Beta 5.