Some simple things, but little timesavers:

  function mk() {
    mkdir -p $1 && cd &1
  }

  alias gpm='git pull master'
  alias gcm='git checkout master'
  alias grh='git reset --hard HEAD'
  alias gs='git status'
  alias gd='git diff'

  alias h='history | grep' # Use like, "h ssh" to see all ssh in your history