Online auction site eBay has launched a a new tool that makes it easy to find out how much an item is selling for on eBay even when you're visiting another site. It's called Browser Highlighter, and here's how it works. You download and install the tool, and then when you're searching for items on selected sites, a "compare on eBay" button will appear. Click the button and a window will pop up over the web page you're currently reading with a list of eBay items matching the term you were searching for.

Browser Highlighter doesn't work with every site on the web. But it does work with Google and Yahoo! search pages, Google and Yahoo! shopping pages, Amazon, and Nextag. Say for example, you're searching for an iPod. You can search Amazon for iPods, and see a list of items matching your query on Amazon. Then you can click the compare on eBay button to see if you can find a better deal on ebay before making your purchase from Amazon.

The plugin also comes bundled with the Skype browser extension that lets you click any phone number on a web page in order to initiate a call with Skype. This plugin's been available as a separate download for a while. While you can uninstall the Skype plugin once it's installed, there does not appear to be a way to opt out of installing it in the first place if all you want is the Borwser Highlighter.

Browser Highlighter works with Firefox and Internet Explorer and is available for Windows only. eBay plans to release a Mac version that works with Safari soon.