Hawkwind is another band who most have never heard of, but who were instrumental in the course of rock history. They are cited as influences of many bands of different genres, from psychedelic to punk. They also have an impressive list of former members, with over 40 and a wiki all their own. Apparently, they had pretty visually stimulating performances as well, which were inspiring to as wide a range of artists as their music.
New Album A Day 