I found an addon for Chrome called OneTab that examines all of the open tabs in a window, then makes a background on a new tab with links to the other tabs, closing them in the process and leaving only one open that's only connected locally.
The problem with that particular addon is ... it doesn't work properly. It opens the ONE tab who's link you click on, then seems to delete the rest. I'm not sure what it's not doing correctly, but it's not too useful with that behavior. (I could be using it wrong.)
My only desire would be to have it create thumbnail images of each tab and put them on the form so you can see visually what's there rather than having text URLs.
Something like that would be perfect for Safari to reduce memory and CPU consumption of inactive windows.