I heard about this via LifeHacker and immediately knew I had to add it to my Mac system: a system-wide ad blocker. I've long been frustrated that there's no obviously good Ad Blocker for Safari, as there is for Firefox (Adblock Plus). But now you can install GlimmerBlocker, which works for all browsers, for all apps that use Safari under the hood (eg, my favoured news reader NetNewsWire), and any mobile devices using the internet connection from the Mac. Result!