Althought it's not my interactive shell, I do like plan9' rc. (well, the first version was for UNIX if I recall correctly, but...)
My configuration is pretty small, just tweak the prompt
prompt=('% ' '')
make sure $user and $home are defined
user=$USER home=$HOME
and some aliases
fn git { env git --no-pager $* }
fn m { make $* }
oh, and make the prompt executable!
fn % { $* }