In spirit, here's mine [0], where I maintain a configuration that works in a similar way for both bash and zsh and does not try to make one identical the other[1]. It respects login vs interactive, and is reasonably fast on start (i have a few ideas to make it faster).
It's designed to be lean, DRY, simple and modular. You can use it as is, overwriting you own dotfiles with setup.sh, or you can pick-source each file/feature you want individually (some need a couple vars set, grep for DOTFILES_).
It leverages available software but tries not to break when it's not available. It works under both Linux and OSX.
It includes an implementation of something like vcs_info for bash, leading to a much more configurable PS1 than git's provided bash prompt support.
Its prompt tries to use colors semantically, and keeps things logical and non-cluttered.
If this reads like this is the best thing since slice bread, that's because it is! ... for me. But I'm sure you could find a useful thing or two in there.
[1] I went all the way to hack support of right prompting and reverse-% cleanup on non-newlined output in bash. It works well... most of the time, but when it breaks it's ugly so I just disabled it.
someone please post a rebuttal showing how to do all this in bash with appropriate .bashrc/functions and utility programs like fasd.