Why not practice some Convention over Configuration and assume these commands will always be run from within a valid rails project directory.
Based on this assumption you can drop the following into your .bash_profile (OS X) or some system-wide profile to facilitate some laziness:
# Rails aliasesDon't forget to load it into you current shell with:
$ . ~/.bash_profileNow you can simply run 'console', 'dbconsole', 'server', etc. when you're in a valid rails project directory without having to append that annoying base directory.
Caveat: If similar commands exist on your system or are introduced by a non-rails package a conflict will arise and the alias version of the command will win. Also, TAB-completion now no longer works for these commands and you'll have to type them out in their entirety.