Here’s a helpful MacOSX feature that I finally stumbled upon. If you hold option down while selecting text, you can select an arbitrary rectangle, instead of some number of rows. A picture is worth a lot of words:
This is great for removing extraneous information from console logs (pictured), or copying just what you want. Unfortunately, it does not work in all applications, including Safari and Terminal. A damn shame, but it works like a charm with Xcode, Console, and TextEdit.