SpellReplay

SpellReplay is a TBC/WotLK AddOn that was originally made for Sbkzor in order to backport a retail addon widely used by streamers called TrufiGCD. The AddOn scrolls smoothly and speeds up when multiple spells are used at the same time, making it easier to highlight good plays.

It has been built from scratch to also include and display:

Missed spells
White hits
Spell rank
Spell damage/healing
Mana gains
Pet spells
Poisons applied (or resisted) on Shiv
… and much more.
The additions mentioned above are adjustable. You can also rescale the frame, change its scrolling direction, speed (ie. slower scrolling while casting), and modify the number of spells to display.
Settings are accessible from Interface > AddOns > SpellReplay or by simply right-clicking on the background square.