I spend a lot of time during my day job developing solutions in Filemaker Pro. We've been using tabbed interfaces in Filemaker for ages now, as it's a convenient way to store a lot of information when you've got limited space. So, while struggling with a "tabless" browser and thinking about just how much I like a tabbed interface, I thought, "What if the Mac Finder had tabs?"
Above is a very crude (don't laugh) mock up that I quickly created. Similar to multiple desktops, you could hop between dynamically created tabs. Perhaps a "create a new tab" option, or "send this process to tab..." Just thinking out loud, really. So am I crazy? What do you think?