That's a great idea! I also play in a lot of bands, and use WheresTheGig to coordinate all of my gigs. I put the band I'm playing with in the gig "Client" field so it shows up on my gig list, but I can see that using the event name would be a good way to do it.
I'll put your idea on my TODO list. I'm currently in the middle of a pretty involved feature request; to provide a staffing feature, which is a bit like the personnel assignment but a lot more complex. I'll see about getting your request in when I finish that up.
All my best,
--Ethan