Imagine being able to get through security at your workplace by using your smartphone. Or never having to queue to renew a smartcard, such as an Oyster card - or even needing an Oyster card.
Imagine the billing being done through the mobile device, and the payment being taken care of through the handset, too.
No need to fiddle with change, or feed meters, or carry cards or cash.
We've moved a step nearer that world with the release of the flagship Android phone from Google, the Nexus S (left), which I laid hands on last week.
While its credentials as an iPhone challenger are impressive, it's the inclusion of Near Field Communication (NFC) technology that is especially interesting.
NFC opens the door to mobile ticketing, mobile payment, even mobile ID, and the Nexus S is the first Android handset to support the technology.
It also opens the door to some significant security issues which have been exercising cryptographers and have until now delayed its introduction.
Having NFC in the device isn't much use on its own, and it's anyone's guess as to Google's ultimate intentions - but it does show direction of travel for the technology.
One suggestion is that it ties in with Google's roll out of Hotpot - a local recommendation engine that works with Google Places. Window stickers in the Hotpot business kits come with built-in NFC for potential rating and recommendation feedback.
That on its own isn't enough to justify its incorporation and it's why the rumour mill is rife that it heralds a move by Google into 'pay-by-wave' mobile commerce.
If true, it begs two questions:
How will competitors respond?
And why does any of this matter to the BBC?
We already have the answer to the former: Nokia has said NFC will be built into all of its high-end smartphones from this year. Similarly, RIM is considering it for BlackBerry; Orange is introducing it to Europe; and three US operators have already banded together under the brand name Isis.
Speed of adoption will depend partly on assurances about security and privacy. But also on how NFC is carved up. Telcos and handset manufacturers are keen for a piece of the action and that could play into Apple's hands with its walled garden approach.
As for the second question, all this matters to the BBC because it's an important milestone in the evolution of mobile - one that will cement its position as primary technology and as part of a wider revolution in the way we receive and act on information.
Google is already a 'mobile first' company. It sees the future of computing as mobile. And for CEO Eric Schmidt that means putting his best people on mobile. Google is already exploring the complexities of location and context in delivering filtered information. The goal is relevance.
It's why, before you've finished entering a search term, Google will have anticipated what you might want.
Start typing the word 'museum' and you'll get a different outcome depending on where you are.
In news, we need to think a lot harder about relevance and move away from treating everyone as if their needs are identical. They're not.
And we need to start thinking about increasing the effort and commitment that goes into our mobile services.
