WowAce

GotWood

Niagara

Displays the zone level ranage of the zone you are in and also gives you a suggest zone and instances to be in.

Provides more visible access to dungeon and raid difficulty settings via FuBar.

Show coordinates on minimap

opens/closes all bags when at merchant (instead of only the backpack)

Track any items you want in a tooltip

A raid buff tracker

Displays a grid of guild ranks versus permissions.

DarkCandy

Allows you to create icons, which can be customized greatly by user's input. CiR is more than just the usual cooldown tracker.

rSelfCast

"Shows Call To Arms status in an LDB data provider."

Provide plenty of links

Group interrupt cooldown tracking.

Add in keybindings to place raid marks on mouseover, or the target if there is no unit being moused over

Add TomTom Waypoints for Flight Masters in classic

EnvenomX

Detox

Don't underestimate your little critters!