For those who want something even less obtrusive than an elbow-height object you might bump, this triangular alternative by Peter Bristol sits at the intersection of not two but three planes – two walls as usual, but then your ceiling as well. Aside from the cord (which you can drop down right along the intersection of those walls anyway), the result sits entirely out of the way, while providing ambient illumination from above.
In some cases, though, a corner-specific design is self-limiting as well. With ladders, you may find that the ability to use it in a corner is only useful sometimes, and that it needs to work well on flat surfaces, too. Thus, this clever dual-purpose design by Arthur Analts which does both on demand.
From the realm of the more experimental (and consequently improbable), here is a bold idea: a corner door. It seems a little less practical, but it also begs the question: why not? The concept is part of a larger project by artist Nicolai Wallner, other examples of which are shown above.
Finally, one last lamp for those who enjoy a bit of a creative twist on tradition – this quarter-cut lamp by Ji Young Shon looks just like its typical rounded cousins, but represents a slice of the circle that slots neatly into a corner.