Bridged DSL connection router

[WiKKed]

Does anyone know if there is a hardware device (router) that would allow to have 2 DSL lines or a DSL and a cable modem connected to and have it automatically load balance and provide a means to double your overall bandwidth, without having to assign certain machines to one connection and certain machines to the other. I have heard of hardware like this but I have never seen it. If someone could provide a link to a manufacturer that would be great. Thanks.