For those of you not on a Mac and not using TextMate vim is an excellent alternative. I modified my .vimrc to be a little more ruby friendly and also added in a line for a dark background terminal. Even though I use TextMate, I still use vim for quick edits. Hard to break old habits I guess.
set background=dark
" Use Vim settings, rather then Vi settings (much better!).
" This must be first, because it changes other options as a side effect.
set nocompatible
" allow backspacing over everything in insert mode
set backspace=indent,eol,start
" set ruby size tabs
set tabstop=2
set sw=2
set autoindent " always set autoindenting on
set nobackup " do not keep a backup file, use versions instead
set history=50 " keep 50 lines of command line history
set ruler " show the cursor position all the time
set showcmd " display incomplete commands
set incsearch " do incremental searching
" Don't use Ex mode, use Q for formatting
map Q gq
" Switch syntax highlighting on, when the terminal has colors
" Also switch on highlighting the last used search pattern.
if &t_Co > 2 || has("gui_running")
syntax on
set hlsearch
endif
" Only do this part when compiled with support for autocommands.
"if has("autocmd")
" Enable file type detection.
" Use the default filetype settings, so that mail gets 'tw' set to 72,
" 'cindent' is on in C files, etc.
" Also load indent files, to automatically do language-dependent indenting.
filetype plugin indent on
" For all text files set 'textwidth' to 78 characters.
autocmd FileType text setlocal textwidth=78
