You know the three obvious ones: Bad Company, Black Sabbath, Iron Maiden
I've been at this question for a long time. I often ask it around parties, camp fires, or when people look bored. Another four I know of because I own the vinyl albums:
1 - Autosalvage- from NYC Around 1966 (hard record to find too!)
2 - Lucifer's Friend - German band from around 1970, whose members are also involved with another outfit/ project called Electric Food. Which is also around 1970. These guys would tour, record, and "Be" with these bands all at the same time. Talk about commitment! What a workload.
3 - Universe- A British band from Wales in 1970. These guys used to be called Spoonfull in the '60s. An original vinyl record of this band goes for about $1000. Hell, even the repressed vinyl I bought cost over $100.
4 - Sea Train - was the aftermath of the blues project. Say....'69-'70.
Most of my research is off the vinyl album covers and liner notes with the record. And to fill in some of the blanks, used Discogs, but only for the corrections and a few dates.