I would sometimes see Chet Helms at events around San Francisco, often taking photographs (like at this reading last December about the Cockettes). Over 5000 of his photos are online.

There is a tribute to him in Golden Gate Park on Sunday, October 29th from 9 am to 6 pm pacific time. It will be webcast if you can't make it in person. It will also
be streamed again at 9 pm.

Performers and speakers include Paul Kantner, Eric Burdon, Dan Hicks
and the Hot Licks, Country Joe McDonald, Ramblin' Jack Elliott, Stephen Gaskin, Howard Hessman, and Wavy Gravy. A full list and schedule is online.

From the press release:

Chet Helms was one of the founding fathers of the psychedelic movement... As promoter for the "Family Dog", Chet developed the concept of the modern rock concert and was one of the founding fathers of the 1960's peace movement that swept the nation and made waves around the world. Chet was also the catalyst that brought together Janis Joplin with Big Brother and the Holding Company, which helped shape the San Francisco sound. Without Chet Helms, as many have said, there would be no Grateful Dead, no Jefferson Airplane, no Big Brother and the list goes on and on.

He promoted other acts such as the Charlatans, the Great Society, Jimi Hendrix, The Doors, Peter Tosh, The Clash.... Helms continued promoting pivotal concerts through four decades. In the 60's at the Avalon Ballroom, Family Dog at the Beach, S.F. Golden Gate Park, Denver Dog, and Crystal Ballroom in Portland.

Joel Selvin writes about Helms (it would be nice if the Chron had all of their coverage of him in one place).

There are a few more photographs I took of him towards the bottom of this page.