I responded to their Craigslist ad about a month ago and set up an audition. They said everyone would play at least Heartbreaker, Since I've Been Loving You, and Black Dog. I had never learned those beyond the main riffs, so I rehearsed them into the ground for a few weeks and brushed up on a handful of other Zep songs I'd played in the past.
At the audition, we played the three above as well as Bring it on Home, Immigrant Song, and The Lemon Song. They liked my playing, and I was proud of how I did. They've been playing together for three years, and they sound awesome, particularly Jason Ott's vocals. I think the vocals are the toughest element of any cover or tribute band, and he's got it down. I left happy; I knew my chances were good, but even if I didn't make it, it was a damn fun hour of jamming with a solid band on some of my favorite music ever.
Jason called me today after they finished their other auditions, asked some followup questions, and called back later to offer me the gig. WAHOO! I have excitement. And I have a long list of songs to learn in the next month. And a violin bow to purchase.