Video game roles for Dave Wittenberg I can recognize him in are Ar tonelico as Don Leon, Persona 4 for Teddie, Welkin Gunther in Valkyria Chronicles. Anime roles well Kakashi in Naruto, and Kaoru in Ai Yori Aoshi. I'm sure I probably heard his voice more then just those.
Liam O' Brien- Ar tonelico as Ayatane, Vayne in Mana Khemia, Stahn in Tales of the World, Chaos in Atelier Iris 2, Count Waltz in Eternal Sonata, and Akihiko in Persona 3. Anime roles Gaara in Naruto, Archer in Fate/Stay Night, Taishi in Comic Party, Vincent in Ergo Proxy, and Shin Natsume in Tenjho Tenge.
So when I think of it this way I just use these examples on trying to guess which character is whom.
(Ok I think I may have got a little carried away when posting this).