Accelerators and WebSlices
Two of the more intriguing new features in the IE8 beta are Accelerators (which were called Activities in the developer's beta) and WebSlices. An Accelerator is a kind of mini-mashup that delivers information from another Web site to your current browser page, or that interacts with another Web site or service. For example, if you're on a page with a street address, you can highlight the address and choose an Accelerator such as Live Maps or Google Maps. The Accelerator will then display the map in a pop-up or open another tab, depending on how the Accelerator has been written for that site.
Not surprisingly, many of the Accelerators that ship with the beta are for Microsoft services, such as Live Maps, Encarta and Windows Live Spaces. But there others as well, including from Amazon, Wikipedia, Google and Yahoo. Any site can write an Accelerator using basic XML, so many other sites may eventually write them as well.
Another intriguing feature is WebSlices, which are like RSS feeds pumped up on steroids. WebSlices deliver constantly changing information to IE -- and as the name implies, they don't deliver it via text, but instead via graphically rich, interactive content. Essentially, a WebSlice delivers a fully functional slice of a Web page to you.
When you're on a page that has one or more WebSlices available, a WebSlice icon on the Favorites bar turns green. Click the down arrow to its right, and you can choose a WebSlice to subscribe to. A listing for the WebSlice then appears on the Favorites bar, and when its content changes, the title turns bold. Click the title, and it drops down and displays the content. You can then click through to go to the Web page that houses the slice, or simply view it in the drop-down.
For example, if you're following an auction on eBay, you can subscribe to a WebSlice of the auction page. When an event happens in the auction, such as someone posting a new bid, you'll be immediately alerted.
In theory, WebSlices are useful, but it's not clear how they will be in practice. At the moment, there are very few WebSlices available, and even those that are available aren't easy to find. Developers have to write code for them, and if they don't, WebSlices will become just be one more nifty-but-useless feature.