Trek communicators from TOS. Taken a look at the flip cell phones?
PADDS - tablet PCs. Also useful for displaying charts and such while
in the cockpit (just to keep this on an aviation topic)
Back to TOS, remember the data cards that Spock and Uhura kept loading
into the computer? Just like 3.5 floppy disks (talk about two-way
nostalgia!)
FTL - Hawking claims he's working on it.
Medical scanners - maybe not as sophisticated yet, but it'll happen.

Of course we're still working out the bugs on transporters....

A number of current and retired members of the US Astronaut corps have
admitted to being motivated by Trek when young.