Ruminations

To you technologists out there: a computer is still not a television, so when and how can I interactively and seamlessly purchase commercial goods relevant to the programs I am watching on television via television?  In other words, if I am watching the Discovery channel, and all of a sudden have an urge to purchase a tent or canoe or sleeping bag, or if I am watching the History channel and all of a sudden feel the need to purchase a book or a ticket to visit some country, how might sites like eBay or Amazon or others place icons featuring items relevant to those shows somewhere on the television (maybe a section of the television program guide might be another place where a category such as relevant "goods for sale" might be placed) which I can access to make a seamless interactive purchase using my TV control, as opposed to having to hassle with logging on to the internet and working my way to finding items relevant to what I just watched?