The Emirates Airline Cable Car runs between Royal Docks and the Greenwich peninsula and whilst it’s not the most oft used piece of public transport it’s still a great experience and something that is well worth doing.
After 9AM the cars which run every 30 seconds and accept 10 people take you on a 10 minute journey across the Thames with great views of East London and the O2 at Greenwich. Before 9AM they run quicker to get people through in the rush hour.
After 7PM they run slightly slowwer still and have music and video in the cabin.
Costs start at £3.50 for an adult ticket and can be paid in the normal ways with a credit or debit card or by using an Oyster card.
If you intend visiting the O2 then I strongly suggest taking a cable car ride, it’s a great experience.