Cheapest iButton (1-wire) adaptor/programmer scheme
Most microcontrollers will do. The 1-wire protocol is not difficult to implement, there are many examples available. A UART will give you serial connection (you'll need a driver like MAX232 to connect to a real serial port). Many microcontrollers have USB device controllers these days, too. Writing firmware that implements a bridge shouldn't be a difficult task (with a possible exception of some existing software that communicates with a reader using an unknown protocol). You can choose one of many commercially available development boards if you don't want to design your own, too.