Along with the super small 2.3.3 bug fix patch going live today a series of new free character transfers have been announced to alleviate the further bloat of certain high population realms:

Source A
Warsong
Illidan
Arthas
Burning Blade
Skullcrusher

Destination A
Lethon

Source B
Mal'Ganis
Kel'Thuzad
Sargeras
Tichondrius
Maelstrom

Destination B
Darrowmere

You've only got until 1pm PST on January 29th, so get in while the getting's good.