Insufficient metrics
I've written before about temperature units.  There are lots of them, and they're not based around a useful zero point.  I hope one day we can come up with a better metric to quantify temperature.  Not only because the units are dumb, but because equal temperatures don't always feel the same.  Temps in the 80s (F) in a humid area feel much hotter than temps in the 80s (F) in a dry area.  Cooking on a metal tray takes a different amount of time than cooking with stone.  That has to do with thermal conductivity and other properties of materials, whereas meteorologists have a pseudo-hack called "feels like temperature".  That's cool and all, but it would be nice if we could come up with a way to rise above these variations. 

Same with Calories in food.  A Calorie is the measure of energy in the food itself.  But I think what would be more useful to know is the nutritional value.  That's obviously a whole other can of worms, but it would still be helpful to have an established metric that showed why fast food calories are not equivalent to real food calories.  (Update:  I'm not alone.) #math

Facebook vs. blogging
Facebook is kind of a like a big room with a bunch of theatrical stages, and each person has their own stage.  The things people post are kind of like them standing on their stage and announcing it to the rest of the room.  It's loud and on a stage, but not everyone notices because they're all on their own stages and there's a bunch of background noise.  Every now and then, someone announces something from their stage and it gets echoed around to other stages. 

Blogging is kind of like talking quietly to yourself while walking down a crowded street.  Most people don't even notice you're there, but every once in a while you'll get a passerby looking for information.  And shouting obscenities in your face. #technology