Do not forget to tell people how to run the thing. How do I start the server? Which port will it be on?
A couple of (complete, with code) examples of common use cases (and maybe a screenshot?) can go a really long way to helping a developer help herself.
For libraries and similar projects such as framework integrations, include detailed documentation of what can be done with this code. Whether that documentation is here in the README, elsewhere in the project, or on the developer documentation site does not matter but it should exist and be clearly signposted from here.