These are like regular socket wrench extensions, except the square drive ends are slightly egg-shaped and let you get onto fasteners anywhere from straight-on to about 15 degrees off. Easily in the running for “Best thing since sliced bread”. Get a selection of them in different lengths.
If you can’t afford a full set, at least get a short one like the one on the right. You can stick it onto a regular extension, and it might save your bacon.
Snap-On has a newer style that may (or may not) appeal to you. In the second from the left, you can see that there is a wobbly section, as well as a straight extension. The wobbly part will push through the socket and engage the straight section, if you so desire. I have a couple of each.