Lots and lots of them, but if I had to pick just a couple to highlight...
1. Event Discovery. What can we build to allow SeatGeek customers to discover the existence of live events they didn't previously know about? Or great deals to those events that they wouldn't have thought possible? A fun mix of machine learning techniques and data engineering gets us there.
2. Consistency. The ticket industry is as balkanized as any industry you'll find. There may be dozens of individual sellers for a popular game; how can we make SeatGeek a consistent interface to all that complexity, so that our customers can get the same good experience for every ticket, for every event in the country?
3. Scale. Every day, we show close to 1 billion ticket listings to our customers, spanning thousands of unique live events. How do we deal with that volume of data and still create a fast, stable, and most importantly *intuitive* experience?