This featuere is coming in the public release.
You will be able to save a generated command line to "My Stuff" (top right corner).
You will be asked for a name (eg. "minimal postgres", "stimulus with postgres and rspec").
For now this will store a cookie in your browser, with the name as the key and the command line as a value.
Upside: lightweight - no need to log in, add database support etc.
Downside: it will only live in the browser you saved from, you can loose
your cookies etc. If it will be a feature people are going to need (IF they are going to use the site in the first place :-), I might add support for FaunaDB or similar.