After selling one of its best-known apps and making three staff redundant recently, Ryan Carson’s Bath-based web studio Carsonified is now flogging another service, Amigo, and has picked eBay (NSDQ: EBAY) as the sales channel. Amigo lets advertisers place ads in mailing-list newsletters, and lets publishers of those newsletters profit from the deal. But Carson says it’s “failed pretty badly”: “We were naive and we thought we could run it in our free time. You can build a web app in your free time, but you sure as hell can