It occurred to me that I hate when a website opens a new tab/window when I wasn't expecting it. The main offender for this is target="_blank", so I wrote a quick Greasemonkey script to convert these attributes. Let me know if you use it. I don't care, but the comments make me look popular.
You'll obviously need Greasemonkey or Creammonkey or Fluid.app or something that accepts GM scripts to use this.