The Salesforce developer team is organising a global hackathon event called 'Salesforce Summer of Hacks' powered by BeMyApp.
They are hosting the event at the Shoreditch Village Hall in London on the 25th - 27th July.
The event is free and is a great way for people to pitch ideas, form teams, and build mobile apps while interacting with Salesforce. You can register here: http://bit.ly/2014soh
Please note this is NOT a meetup event so if you want to attend please use the link above to register.