It is reported that Microsoft has patented technology for networking mobile electronic devices through the user's skin. Gear like PDAs, phones etc would communicate by using the skin's electrical conductivity. Further applications could supposedly include producing power for such devices from your movements, rather like a self-winding watch, and even displaying information on the skin.
All very sci-fi, but the problem is obvious. Just wait for the Microsoft security holes in this system to come out, probably when some bunch of Russian students with time on their hands develop a hack that makes you come...out, or streams porn ads on your forehead. At least it will be a great new excuse, though. "How can I ever make it up to you, my love...I swear I must have opened an e-mail attachment or something.." "Your Honour, my client contends that his skin network was hacked by person or persons unknown, who gained control of his movements and literally forced him to commit this bestial act.."
Arthur C. Clarke famously said that sufficiently advanced technology was indistinguishable from magic. A corollary might be that sufficiently unwise technology is indistinguishable from paranoid fantasy.