While Eventbrite has a great integration with Salesforce.com, it would be great if there was an integration with Marketo directly so all the tracking can be more easily retained.
Again, and now at another Marketo customer, I add my voice to this choir. As Kanneth states, if you want to deliver better offline event management capababilities I'm all for it since integrations never are pain free. Another thing that we like about the Eventbrite is their iPhone app which allows all our reps with an iPhone to help out at event check-ins. Also, setting up new Marketo user accounts for temps just to let them check people in has become somewhat annoying.
You can create a single login for the temps and have them use this to log into the Event Check in app. There is no need to create separate logins for them.