John Gruber at Daring Fireball has a clever workaround for when you want to have Flash available on demand on a Mac, but don't want it installed by default in all your browsers. John formerly used ClickToFlash with Safari to let him selectively control which Flash content displayed; there's a similar add-on called Flashblock for Firefox. Instead, John removed Flash from the various plug-in directories shared by browsers. He notes that Web sites now feed him alternative content, like static ads, since his browser no longer pretends it can accept Flash only to ignore it. A YouTube extension forces HTML5-compatible video to load, too. When he needs Flash, John launches Google Chrome, which has integral Flash support (it can be disabled, but you can't whitelist or blacklist specific sites). When he's done, he quits Chrome to prevent Flash from chewing cycles in the background.