Hi there, Bianca and welcome to the forums!
That is an excellent question. It’s always nice to hear that people are interested in making email more awesome.
I don’t have any specific examples of how the ticket emails have been customized in interesting and awesome ways. However, whenever I’m in the need for email design inspiration, I often turn to the gallery that Campaign Monitor curates on their site. They also happen to have a handy (and free) email builder that will help you craft the HTML for a new template, which could then be integrated into the ticket email template.
Sorry I don’t have more concrete examples here, but does this help stir the pot a bit?
Cheers!
Geoff