Button groups and Button Dropdowns
One thing that is used quite often when I do custom VisualForce development is bootstrap to aid in styling. A feature that is really nice and helpful to conserve space is button groups with dropdowns. Basically I have a row of buttons atop of my record pages and once I get 4-5 buttons it takes up the whole page a lot of the time. Adding button grouping to page titles, wherever buttons can be used would be an extremely beneficial feature.