What's the most creative customer acquisition strategy you've come across?

Even though it isn't creative. Applying a freemium pricing strategy was a good idea.

Free standalone tools often end with creative approaches to attract new customers

Uber's free rides program way back when they launched helped them become well-known, quickly. Within a few weeks, it seemed like everyone I knew was aware of them, and using their service - seemingly out of nowhere.

Offer Some free perks like telecom companies offer free internet data and minutes with every package they sell.