I had the same idea about a cookbook and I think I found a great name for it.
# Mission
It is a bit different from what Lassi found in the sense that it is not
how-to things that very specific and most of the time depends on the
implementation.
Unlike SRFIs it will not be a set of libraries that are discussed and
proposed to the community.
It will tutorials on how to build an applications with code and documentation.
# Setup
For that project to succeed, it must be extremely painless to run and test
the application itself. That is it must have Continuous Integration and a
standard way to run the code.
That's where things becomes really overwhelming. Getting together
with the tutorials, we would need a way to resolve dependencies maybe
even non-scheme dependencies and install them in user home directory.
Guix requires sudo to install it. Also, it is not portable across schemes
or kernels. I read there is a GNU Hurd port and maybe xbsd port. but no
windows. It is also a GNU/Linux distribution, reproducible, bootstrap-able
and PID 1 (via GNU shepherd)).
Also, I don't think that other scheme implementations will be keen on
using it, for the above reasons and also because of Not-Invented-Here
syndrome.
The immediate possible solution I had in mind is: guix.
# Conclusion
Having more toy applications will be a good thing.
Maybe, given the particular constraints of 500LOLS, getting
together only a portable user-space functional package manager
is not impossible.