Like most people, I use mutt and vim for email! Vim 7 added nifty inline spell checking, so I made it automatically turn this option on for mail by doing the following:

mkdir -p ~/.vim/syntax/after
echo set spell > ~/.vim/syntax/after/mail.vim

These key bindings make tab switching the same as that of Firefox, at least on my computer where ctrl-tab is eaten by the window manager.

map <Ctrl-PgUp> tabp
map <Ctrl-PgDn> tabn

Enable scroll wheel goodness and selection.

set mouse=a

I almost never use octal and hex, so disable auto-detection of these for the Ctrl-A/Ctrl-X increment and decrement functions.

set nf=