Forever Simple Timers

Forever Simple Timers gives you two tiny boxes you can move anywhere in World of Warcraft: Forever. In game it is listed as Forever Timers.

• Mana box. After you spend mana, an estimate of the pause before full mana regeneration resumes (~3.2, five seconds by default and adjustable). It works from each spell's public mana cost, so it is an estimate, marked with ~.
• GCD box. The time left on your global cooldown, read from the game when it can be, and estimated (~) when not. It learns a few of your spells that have no cooldown of their own, so it can still read the GCD after spells like wand Shoot.
• Spell lockouts in red. When an interrupt or silence locks your spells, the GCD box turns red and counts it down; full-text mode names the school or effect (Fire 3.8s, Silenced 2.1s).

Each box can be locked, sized, hidden when ready, or shown as tiny or full text. Neither timer casts anything for you.

Every setting is in Options → AddOns → Forever Timers (or /ftimers).