The Harry Potter books mention that the Weasleys had a clock telling them the status of various family members (work, hospital, mortal peril, etc.). At one point after Voldemort's return, all of them are listed as being perpetually in mortal peril. For example:
‘Then you just buck up your ideas, young man, before I decide you’re too immature to come with us!’ said Mrs Weasley angrily, snatching up her clock, all nine hands of which were still pointing at mortal peril, and balancing it on top of a pile of just-laundered towels. ‘And that goes for returning to Hogwarts, as well!’
Ron turned to stare incredulously at Harry as his mother hoisted the laundry basket and the teetering clock into her arms and stormed out of the room.
-Half-Blood Prince - Chapter 6: Draco's Detour
Wouldn't that significantly diminish the usefulness of the clock? After all, wouldn't it be possible for someone to be in greater or lesser degree of peril? Wouldn't they want to know if someone was in particularly grave danger (e.g. an imminent battle with the Death Eaters)?
Also, wouldn't you want to know their secondary status? For example, you could both be in the hospital and in mortal peril (recall the guy who was murdered at St. Mungo's in the 5th book), but the clock doesn't seem to be able to represent that.