Browser UI features are getting consistent

Cross-browser issues are caused by browsers not complying with W3C standards while rendering pages. Increasingly however the browser UI features are getting consistent. If a particular browser brings out an innovative feature that is lapped up by users, chances are the rest of the browsers would implement it too. Here are some examples -

Pop-up blockers - At the height of the pesky pop-up window scourge inflicted by unscrupulous webmasters for making money out of ads, there were paid tools to prevent pop-up windows. IE 6 started having a in-built pop-up blocker & so did other browser versions that came in that period.

Inline Find, Find As You Type - These were some of nifty features that endeared me to Firefox. IE8, Chrome, Safari now also sport this feature. Opera (v 9.6) still retains the intrusive Find dialog box.

Inline Spell-checking - Firefox, Safari & Chrome point out spelling mistakes with red squiggles as soon as you finish typing a word within a textbox or textarea

Search from Address bar - Google Chrome introduced the "Omnibox" feature that lets you use the traditional address bar to type your search keywords as well. IE 8, Firefox (v 3.6), Opera (v 9.6) now support this feature.

Keyboard shortcuts - Several of my favorite keyboard shortcuts are the same in Firefox 3 and IE8. The shortcut Ctrl+Shift+T lets you re-open a tab that you may have accidentally closed in Firefox, IE, Opera & Chrome.

Moving Tabs around - Opera was the first among the popular browsers to introduce tabbed browsing. I guess, Chrome brought the feature of dragging a tab & dropping it at any other place in the tab list. Now all the new versions of common browsers let you move tabs around.

Caret Browsing - IE8 & Firefox let you select text & navigate line by line using the keyboard. This accessibility feature can be toggled on or off with the F7 function key.

Hidden menu bar - IE, Chrome, Safari on Windows (ver. 4) do not display the menu bar by default to conserve browser real estate.

Child tabs open immediately after Parent tab - When clicking on links within a web page to be opened in a tab in IE8, Firefox 3.6 & Chrome the child pages spawned from the referring page will immediately precede the parent tab rather than at the end of the tab list as it used to happen in older versions of IE & Firefox.

Private Browsing - IE 8, Firefox (3.5 & above), Chrome, Safari on Windows (ver. 4), Opera (10.5) will not let anyone know about the secret sites you browse by not storing them in your browsing history when you enable this feature.

A context-sensitive option to send highlighted text within a webpage as query to Google/default search engine now appears in all popular browsers (IE, Firefox, Safari, Opera, Chrome)

Paste & Go is a context-sensitive menu option that appears when you try to paste a URL onto the address bar in Chrome, Firefox (version 4 & above) & Opera (keyboard shortcut Ctrl + Shift + V in version 11). It saves you the step of having to hit the Enter button after you have pasted the URL in the address bar. (Update - 1/Sep/2011)

The browser versions I've specified in the examples above are the ones I've tested on. It's possible that a particular feature may work in a earlier version as well.

Also see:
The Collective Decisions of Competitors