A nice configuration for tmux 1.5 and later.

.tmux.conf

# Use backtick as control character:
set -g prefix `
unbind C-b
bind ` send-prefix

# Config reload key:
bind r source-file ~/.tmux.conf

set -g history-limit 7500
set -g default-terminal "screen-256color"
setw -g aggressive-resize off

set -g status-bg black
set -g status-fg white
set -g status-interval 1
setw -g monitor-activity on
set -g visual-activity on
set -g status-left '#[fg=green,bold]#h:#S#[default]'
set -g status-right '#[fg=yellow]#(cut -d " " -f 1-4 /proc/loadavg)#[default] #[fg=cyan,bold]%m-%d-%Y %H:%M:%S#[default]'

setw -g window-status-current-bg red

set -g mouse-resize-pane on
set -g mouse-select-pane on
set -g mouse-select-window on
set -g mode-mouse on
set -g mode-keys emacs

set -g set-titles on

set -g renumber-windows on