So I keep experimenting with the new three finger trackpad swipes, and came across the following in Safari. Command and three fingers swiped to the right or left will create the forward or backward page in a new tab. Option-Command and a three finger swipe (left or right) opens the backward or forward page in a new window behind the current one. Finally, Shift-Option-Command and a three finger swipe (left or right) opens the backward or forward page in a new window in front of the current one.

Obviously, for any of these to work, you must have a page or pages in the forward and/or backward buffers.