GNOME shell have current running windows mode like in Mac and I love it, but I don't wont use GNOME Shell, may be have some way to display the current running applications as well and in Unity.
You have to install Compizconfig Settings Manager.
Then, run compizconfig Settings Manager and go to Window Management -> Scale plugin. Now, under the third tab - Bindings, you can configure the window picker you want with any corner of your desktop. If I understood you correctly, you would need to click on the fourth entry, "initiate window picker for all windows" and choose the Top-Left corner.