The stats for audience per a band and per a venue is the top feature of this site.
Adding fellows to a gig record is a great feature in this connection. Unfortunately, I'm not going to use it with the e-mail requirement.
I realize that the e-mail proves the existence of somebody and prevents adding numerous phantom spectators just to increase the audience of a certain band. No matter of that, I don't want my fellows to be attacked by e-mail with various invitations which is probably the main purpose of that feature.

Instead, I can suggest adding an option within proved serious user accounts to register, let say, up to 5 fellows with nicknames and avatars (I mean not as a separate new accounts but as a group of friends within a proved account). So, when in a gig page and click on this feature, it opens a list with your registered fellows to be selected. This will increase the value of the stats as well as the joy of using the site and keeping record for your friends and relatives along with yours.

I'm a fan of this feature because I am such a fan of the existing histograms and statistics. I have plenty of friends that aren't going to consistently use ANY service to track things like this — but I would still love seeing how many concerts I've been to with Vince over the years. I'm not sure how to accomplish aside from each CA.org account having a managed "personal attendees" list that can be tied to a concert with each "personal attendee" having an optional field for email that can invoke the current system. This way, I can say I went with "Ray" and "Vince" but Vince is only tracked locally and Ray is added via his email because he has a CA.org account.

(Plus it gives the option to track which concerts you went to with that girl Molly.) ;)

Is the goal just to record & remember who you went with? If so, you could use the new 'Private Comments' feature to save this information for the time being.

Completely agree with this. I have friends I'd like to list as having attended, but they've either passed away or we've lost touch, so I don't have an email.

add who I attended with without them having an account

Totally agree with this, not wanting to have to add them by email as unfortunately you could have went to a show with someone who is no longer alive. I want to be able to see all attendees to the show without email.

Or rename it "Spam my friends"