My favourite on boarding by far is Duolingo and I see its mentioned here already. We've just spent months researching and re-building our own on boarding at Streamtime so I'm keen to hear what you all think and I'm open to any constructive feedback as well cause we feel we're never finished when it comes to onboarding. http://www.streamtime.net is the url and its a project management tool for creatives.

Our biggest problem is that our product does way too much to show a user on the first run so we took a 'slow reveal' approach to onboarding and tried to direct first time users into just a couple of areas (in our case the creation of a job and then get the user to plan our a TO DO for that job and complete it which illustrates how we track time as an alternative to timesheets.) - this 'no timesheets' message has been troublesome for us to get across so we felt we needed to show how time is tracked quickly. The downside to this is some users dont want to see that - they want to get in and look at things like quoting, scheduling, invoicing etc the more meaty stuff of project management so we needed to create a way for people to opt out of the onboarding experience along the way. As I mention above its a work in progress for us, we are constantly looking for ways to improve it.