I find that the left-side banner on the OSM screen (ie. the vertical banner that contains the “Help, Community, Data” sections) is taking a bit of space when viewed on a desktop computer.
It is planned to remove it completely (as soon as those links are somewhere else). In the mean time you could use AdBlock, Greasemonkey or other kinds of user scripts/user styles to remove/hide the element with the id and class “left_menu”.