I don’t see much point in adding “toys” to a computer using the USB port, unless it’s something that either reports to the computer or can be controlled by the computer. Just using the computer’s USB port as a power outlet seems rather pointless to me, given that you really can’t get much power out of a USB port.
That being said, it’s obvious that there’s a market for all sorts of useless gadgets, such as the USB disco ball (can you set it to operate only when you’re playing Donna Summer or The Village People in iTunes?) and the USB drink cooler (which actually isn’t quite useless, even if they don’t say how long it takes to actually cool a drink).
There are design concepts here and here for USB toasters. Given the power restrictions, I wonder how long it takes to actually produce a piece of toast using one of them. Although the first one looks more like a printer, it appears that the second one is the one that operates as a printer.
I wonder if there’d be a market for slices of bread with an image of Jesus printed on them?