Just a few months ago, Uber made it possible to view Denver's Regional Transportation District (RTD) in its app, allowing riders to search for and plan public transportation trips. This is a logical next step, and it's something we'll likely see Uber expand. If you're in Denver and don't see this option yet, don't fret -- it's a staggered rollout.

To make this possible in Denver, Uber partnered with Masabi, a London-based company that develops mobile ticketing services. Masabi works with 30 transportation agencies worldwide, including many in cities where Uber has a strong presence. Given the Masabi connection and that just this week Uber added London's public transit to its app, we might guess that London will be the next city to see the expanded in-app purchases.