Previews is a Firefox add on that provides you with instant previews of links while you browse.

Every time I surf the web, I come across links that seem interesting, but turn out to be disappointing. CoolIris’ Previews helps me avoid clicking on these links.

Here is how it works:

Once it is installed and Firefox is restarted, whenever you rest your mouse over a link, a little blue icon appears. When I rest my mouse over this icon and the preview pops up. This works so quickly as to be virtually painless.

There is also a built-in search feature: If I highlight word(s) then right-click and select Cooliris Search, I get the option to search Google, Google Images, Wikipedia or The Free Dictionary. And, of course, I get an instant preview of the search results.

The preview window has a toolbar with a lot of handy features:

• A little arrow lets me move to the next link on the page without closing the preview, another arrow takes me back to the previous link.
• I can save the previewed page as a temporary bookmark in case I want to have a look at it later. Previews stacks these thumbnails in a vertical tab on the right hand side of the browser window. The bookmarks disappear when I restart the browser.
• By the click of my mouse I can email the link to my friends.
• A button lets me open the link in a new tab.
• With another button I can lock the preview window so it doesn’t disappear while I browse.

Take a look at PicLens, another tool from CoolIris.
You might also want to take a look at this 4 min tutorial: