Barcode-scanner apps are one of those novelties you download for your iPhone or Android, but never use past that first day. Integrating the tech into eBay's iPhone app is probably the smartest use I can think for it.
The 2.0.0 update to the app has brought many new features, but it's that RedLaser barcode scanning which most excites me. See a product in a shop, scan the barcode within the app, and find it cheaper on eBay—and considering how much of an eBay addict I am, I could see myself using this several times a week at least.
You can also save and share favorite searches, not to mention receive alerts when new items are found in your listed favorite searches. Items can be listed for sale even faster, and the search function has been tinkered with to improve results. It's a free download. [iTunes via Recombu]