While Google is testing search results that update as you type on its own, startup CloudMagic is bringing that functionality to Gmail and Google Apps – and other cloud-based services in the near future – by means of a Firefox and Chrome browser extension.

Installing the extension results in an extra search box in your Gmail interface that allows you to rapidly search for anything in your inbox, with results updating as you type and the ability to preview messages from a thread in a tab or open entire conversations with a single click.

If you’re a Gmail power user like I am, you need to hear no more to realize how useful that functionality is. It’s entirely free, so nothing should stop you from installing either (account credentials are stored locally, and not on CloudMagic’s servers).

I installed it, and while the speedy search and email conversation previews are nice and welcome, the one thing that will make me get used to CloudMagic very quickly is the fact that when you have tabs open with search results, they remain up on top on the right-hand side while you peruse other emails or compose new emails to people.

This basically means no longer having to open another tab to search for e.g. a telephone number in Gmail I’d like to pass on to someone else by email. And if you want to go back to the full Gmail interface, all you need to do is hit the shortcut key (Esc).

That feature alone will save me a couple of hours per month, and that’s a whole lot in my book.

The app is currently limited to Gmail and Google Apps, but will soon be introduced for Google Docs, Hotmail, Yahoo & other cloud services.

Magic? Nah. Terribly useful? Yes, Sir.

(Also check out Rapportive, another plugin that makes Gmail better).