I sorta have this feature in Firefox!
There are two bookmarklets on my bookmarks toolbar acquired from:
http://www.squarefree.com/bookmarklets/misc.html

increment - Increases the last number in the URL by 1.
decrement - Decreases the last number in the URL by 1.

(I renamed them to + and -)

-inertia

the Link Toolbar extension does "navigation guessing" that sounds like the same thing.
http://extensionroom.mozdev.org/more-info/linktoolbar
normally it uses link rel if available, but tries to guess on sites without, and it also lets you jump up thru a site's hierarchy like the Digger extension. all nicely tucked into a panel on the status bar.

That's known as "fast forward" and "fast backward" to Opera. Pretty cool. It "forwards" / "backwards" to the first / last page of the same domain (look at the URL). It is an unique feature (but not necessary) in Opera and I can't see any other browsers implementing this idea yet.

The most impressive improvement in this new version is to support of in XML (e.g. XHTML in application/xhtml+xml).

As a Firefox user, I'd rather use the mouse gesture of up-left-up to move up one directory of URL. ^^:

The reason why I don't like Opera:
- Slow startup speed on my machine (PIII 800MHz, Win2k). It is THAT slow right after fresh installation. I knew there are many reasons listing in Opera7Wiki... but don't bother to "fix" it. (it's not my fault, right?)
- Adware
- Identifical as MSIE by default (look like Opera is not proud of itself)
- Incomplete support of XHTML and JavaScript, e.g. , accesskey of and other elements.
- Lacking some important features, e.g. rich text editing, XmlHttpRequest, syntax highlight in view source. Also some websites look horrible in Opera, but normal in IE and Mozilla.

Hm. Cool features? Here's a random list from me:

Editing pages on the fly (view-source, edit, save, View > Refresh display).

If you enable [Preferences - Page style - Configure modes - Author mode - My stylesheet], you've got yourself a menu full of stuff under View - Style.

You can make the page tabs wrap around from the Customize toolbars dialog. You can also reorder them by drag/drop.

Of course, the mouse gesture for "up one level" exists in Opera - Up-Left. You can edit mouse gestures, along with keyboard shortcuts from the Preferences. Menus from the ini file.

I agree - the fast forward is a killer feature becuse it means you don't have to look for the "Next" link in a list of results and most importantly, in Opera it binds this function to the 5th mouse button so I don't even have to move my hand to use it. I loved this feature so much I suggested it on the mozillazine forum, where cdn and clav promptly found it and produced the linkit extension (and have since integrated it directly into the link toolbar extension). So you can get it via an extension in firefox, but unfortunately it doesn't integrate with the mouse (at least not yet).

For what it's worth, implementing Opera's fast-forward feature is bug 192429, at least at the back end. I don't think there's a bug on file for giving Firefox a UI for this feature...if there is, I'd like to be CC'd on it :).

Piro just implemented this as an extension for Firefox:
http://white.sakura.ne.jp/~piro/xul/_rewindforward.html.en

I have now idea how it works, I haven't tried it.

Roughly a year ago I wrote an informational page about FastForward. It's slightly outdated with regards to the shortcuts, but the rest is still correct:

http://www.markschenk.com/opera/fastforward.html

You'll also see information about Opera's slideshow feature there: when you are on a page with links to image files, FastForward will detect this and allow you to navigate through all the images easily.

For instance look at this page and hit FFwd a couple of times. If you're tired of looking at the images, just hit Rewind and you're back where you started :)

I'm a opera-user, and i must admit that your first post on opera annoyed me. What annoyed me more was the pointless "discussion" in comments, where very little useful was said. But back to you wanting operausers to show you around in opera a bit, i would strongly recommend checking out the irc channel #opera on irc.opera.com...lots of great people, try it and we will make sure you don't regret trying opera :)

Catching onto this thread late in the game, I hope this helps. If you turn off the main toolbar and add a couple of icons to the mini-toolbar, you have all of the controls but the advertisements are only a centimeter tall. Here's a screenshot that also shows how I found your site. Also, the Design Detector has a useful writeup of recommendations for setting up Opera 7.50. I'll be linking to these threads from this post on my site. Cheers.

Hmmm. Have you been using Firefox recently? ;)

http://downloadstatusbar.mozdev.org/eznav/

The "snap back" feature is also in the Firefox Google toolbar extension. You can create a "landing" page that you can snap back to at any time - sorta like a session-based "home" button.

One thing nice about Opera, that I haven't seen in other browsers is that a web designer can attach different stylesheets to a page and you choose your favorite for rendering that particular web page.

For a real-world example, please visit: http://geocities.com/csssite/alt.xml and then click on the icon and choose from one of the three stylesheets at the bottom of the popup. Although that Opera has not implemented the whole CSS2 spec yet and has some bugs with the implemented part of the spec, IT REALY ROCKS!

I love the full page zoom as well! Yes the fast forward is available for FF but the ones I've seen just increase the number, eg., image 1-2-3 and don't seem to use whatever algorithms Opera does...does Piro's extension fix this?

Behrang, Mozilla and Firefox have had that feature (select from alternate stylesheets) for as long as I've been using either (several years).

If you don't visit Dilbert.com daily, fastforward is also very useful. Click on 'read past strips', click the oldest entry, then press Space. Space. Space. etc until you've seen the latest 30 strips.

If you bash Opera, what do you expect from the devoted users of that browser? You are the one who blames Opera. I was suprised that you focus on other browsers before gaining any significant market share from IE. I guess mozilla started to lose its focus, no wonder why AOL ditched you.

Opera has one feature I love, but it’s not nifty or cool or anything like that. Opera hangs initial quotes, so they start outside the left margin. It looks classy, and I wish Firefox did it too.

I think one of the coolest feature in Opera (Opera has many cool features) is the REAL ZOOM, not only larger/smaller text. It is very usefull for people with resolution higher than 1024x768 and for other purposes too (zoom on images, to large sites, etc) And it's easy handled with only 3 keys: +, - and * on the numerical keypad (* is 100%)!