With OmniSellerEbaySearch you can search items on ebay if you write a keyword into the searchbox. If you press enter the search request starts and shows you all results. You can search for min and max prices.
Search, track and bid on eBay items
eBay Mini Widget – Search all of eBay.com’s auctions from your Dashboard
Popular eBay Items – Browse eBay from Dashboard
Free Mac OS X widget that will bring eBay to your desktop
eBay Sherlock Plug-in – Search the auction site eBay with this Sherlock plug-in