like the olsen twins, sometimes good things come in pairs.
first, i discovered pow - the zero-configuration rack sever for OSX from the nerd heros at 37signals. symlink a project directory once to your ~/.pow directory, and it will take care of everything for you. no need to fuddle with /etc/hosts or anything else, all apps on your machine will be runnable simultaneously through a url structure of http://{appname}.dev. and like any modern development rails set-up should, it also offers full integration with rvm and bundler.
5 minutes later i discovered powder is a gem for making pow even more convenient to use. the commands speak for themselves =>
$ powder
=> Link the current dir_name to ~/.pow/dir-name
# if the dir_name has underscores in, powder changes them to hyphens
$ powder link bacon
=> Link the current dir to ~/.pow/bacon
# If the current directory doesn't look like an app that can be powed
# by pow it will offer to download a basic config.ru for Rails 2
$ powder list
=> List all the current apps linked in ~/.pow
# aliased as powder -l
$ powder restart
=> Restart the current app
# aliased as powder -r
$ powder open bacon
=> Opens http://bacon.dev in a browser
# if you have set up alternative top level domains in .powconfig,
# then the first listed domain will be opened.
$ powder log
=> Tails the pow log.
# Not the application log, but the pow log, available at
# ~/Library/Logs/Pow/apps/app-name
$ powder install
=> Installs pow server
# (I know, "curl get.pow.cx | sh" isn't hard, but this is _even_ easier)