Nice set of guidelines from Apple on mobile design and development.
A pretty comprehensive set of UX guidelines for the BBC produced by Neville Brody and team at Research studios http://www.bbc.co.uk/gel
A really nicely produced set of guidelines from the UK Government Digital Service Group. https://www.gov.uk/designprinciples Start with needs Do less Design with data Do the hard work to make it simple Iterate. Then iterate again. Build for inclusion Understand context Build digital services, not websites Be consistent, not uniform Make things open: it makes things better