Arduino + Ethernet
Being able to plug an ethernet jack directly into an Arduino opens up soo many possibilities. Until just now, I thought the only way to do that was to buy a $100 ethernet to serial board.
I happened to stumble across a much cheaper solution, which definitely must be explored further!
This is just the shield for the Arduino, the actual XPort jack is sold separately. I thought I found a place that sells them for about $20 - $30, but I can't find it at the moment.