safely remove USB hard drive

[Joe Smith]

When I attach an external USB hard drive, each partition on the drive is 
mounted separately, under /media.

When I want to remove the drive, what's the simplest way to be sure that 
all cached data is written/cleared, so that I can safely remove the drive?

I've been using eject /media/* but that only happens to work because 
nothing else is mounted there.

Suggestions?

<Joe