Thinkpad: THE single best use you can have for the outdated ExpressCard 54 port on
THE single best use you can have for the outdated ExpressCard 54 port on a ThinkPad: the Mogo Mouse X54, a bluetooth mouse that fits in the EC slot and charges inside the slot when not in use. The best portable mouse is the one you forget you have with you until you need it.
Ain't the most ergonomic thing, but it's useful when you're in a cramped space, or too far from the machine... It's better than none, and it's just as uncomfortable as one of those slim mices you'd toss in your bag and forget to charge.