With 1.7 and the new 1.8 snapshots, Mojang is adding a lot of new commands and uses for command blocks. I've just recently started to really get into using them, and I think they're just amazing.
However, what isn't amazing is having to remember/copy down coordinates. Sometimes you forget and have to re-check, sometimes you get something wrong and completely mess up a design, and sometimes the daunting task of copying down dozens of coordinates discourages you from starting a project to begin with.
My suggestion is simple- assign a hotkey (If forced to choose, I would probably use "\", but I don't suppose it matters) that copies a player's current block coordinates to the clipboard, where they can then enter a command block and simply Ctrl-V and paste them in. This wouldn't just be for command blocks, however. It would also allow players to easily post coordinates in the chat, on signs, on the web or in text files, etc.
So, what do you think? Support? Concerns? Is it already in the game and I'm just an idiot and don't know about it?