While Sidebars can sometimes take up a fair amount of real estate, the eBay sidebar actually works pretty well, because it's something you'd only want to open when you need it to take a look at all the items you're selling, watching, or bidding on. For most actions, you can rely on the alert boxes that will pop up when you need to take action.

You can set the Companion to send a popup notice when an item you're bidding on or selling is about to end, when an item you're selling has been sold, or when you've been outbid by another buyer.

The sidebar doesn't have to be open to receive these alerts.

When the sidebar is open, you can search eBay or look at your account. You can set the Companion to either open your search results in your current tab or a new one.

Auctions that you're currently participating in or that have recently ended show up in the sidebar with some basic information like the current price and how much time is left to bid. You can also place a bid or "buy it now" directly from the sidebar.

When you scroll your mouse over an item, more information pops up including a complete title and bid history.