There are a total of eight different raids in WoW WotLK. All raids can be completed again in 10-man, 25-man as well as Normal and Heroic modes. So, you can have four different ID's for each raid. The eight raids are:
Vault of Archavon,
The Obsidian Sanctum,
Naxxramas,
The Eye of the Eternity,
Ulduar,
Trail of the Crusader,
Icecrown Citadel,
and also Ruby Sanctum.