I recommend:
https://github.com/teambox/teambox/tree/dev/features
Update: As mentioned by Ivailo Bardarov, they use websteps which is a bad practice at present. Just look at this as a reference to see good features and not steps!
Update 2: I think off-late, I learned a lot from following cucumber features provided with paid version of Object on Rails book. The source code is not open-source so I cannot post it here or could not find a link to it.
My preferred way is to keep feature language close to domain / business language rather than specific steps or filling in form. So instead of having something like this in my features:
When I fill in "Name" with "XYZ
I will have my feature say:
When I create a project:
| name |
| xyz |
And then my step would have, the code to click the link, parse the table and fill the relevant form field etc.
