The traditional bench-mounted vise, protruding as it does from the worksurface, is always in the way when you're not using it. And over time they can start to sag, which gets annoying. (The ones we had in the ID shop at Pratt did that thing where they got higher as you started to tighten them and lower as you loosened them.)
Workbench manufacturer Benchcrafted's Tail Vise is a clear design improvement. Integrated into the bench itself, the Tail Vise holds a dog block (that's on you to provide) meant to correspond with a row of dog holes in your bench.
One cool thing is that the screw doesn't move in and out of the table as it's turned, instead maintaining its position in space. Another cool feature is the cast-iron wheel, rather than a T-handle; the wheel affords greater precision and lets you more quickly crank a full revolution.
Here it is in action:
You probably won't be retrofitting this to your existing bench—unless you've figured out some clever way to cut stepped dog holes into your already-assembled work surface—but those starting from scratch will definitely want to look into one of these.