If you do find yourself in need of some support, here are several options.
For 3.1.x
In addition to class level documentation, the project wiki also provides several Getting Started tutorials to help you understand how the pieces fit together, and contain some very basic examples. This should be the starting point for anyone new to Grapevine.
For 4.x
See the new project website.
I'm on the StackOverflow Q&A boards regularly, as are several other individuals with experience using Grapevine - and an even broader community of people with experience using C# and REST who generously take their time to respond to the question and problems of complete strangers without asking for anything in return. Use the #grapevine hashtag to post your question there - don't forget code examples - and someone (who am I kidding? probably me) would be happy to help you find your way forward.
Did you find a defect with Grapevine? Man, that's gotta be embarrassing for me, right? Do me (and everyone else) a huge favor and use the Issues feature on GitHub to let me know what you found and how to reproduce it. One of the many great advantages to this approach is that you can follow the progress of the issue over time. Remember, the more detail you can provide, the faster I can provide an update with a fix or another solution.
IMPORTANT: Please use this option only for code related issues, not usage support requests.
Grapevine is open source, and quite a few people that have found Grapevine useful have also generously given back to the community by sharing the enhancements they have made. Great contributions, everyone, thanks! If you've made an improvement to Grapevine that you'd like to share with the rest of the community, create a pull requests and our team of enthusiasts (yeah, still just me) will take a look and maybe even pull them into a future release.
If you have a great idea for an enhancement, but don't know how to implement it, create an issue and tag it as an enhancement, and maybe someone else will pick it up and add it for you.
Whether you're contributing code or just an idea, providing a clear and detailed use case and usage examples is going to be paramount in deciding if and when your contribution makes it into the core library.
Depending on our availability, sometimes pull requests will sit in the queue until we can get around to reviewing them and merging them into the master branch. I appreciate your patience with my time as I endeavor to ensure that Grapevine remains a stable, high-quality and reliable solution.