Selectrics also had what is easily my favorite font, Artisan 12, which is kind of like a perfectly rounded (in the case of 'o') Letter Gothic variant to my rather untrained eye. It's so emblematic of an entire era in computing and I use a crude personal version of it regularly to make my terminals feel more retro.

Low res example of the classic: http://luc.devroye.org/IBM-Selectric-artisan12.gif