all the booster packs have "permanent" temp powers in them, i'd suggest maybe looking to see which "permanent" temp powers your characters have in the powers menu and compare against the booster descriptions.
also, not sure if the packs are dated when they were released in the store, but you could narrow it down by eliminating packs that came out after you left.
Offhand, you can check the list of booster packs at http://wiki.cohtitan.com/wiki/Booster_Packs and see which of the various abilities you have.
Thanks Thug...that site actually helped me out and I figured out which ones I had.
Ok so I saw the new Going Rogue expansion and it looks intriguing and so thinking of coming back to the game. I was looking at the store and I saw some booster pack downloads also, I remember I bought one of them back when I played the first time around. Is there anyway to see exactly what I have bought in the past? I looked through the account management section and noticed all my serial codes that were listed including 2 Perks (which I am assuming are the booster packs), but it did not list which ones they are. Any ideas of how I can figure out what I already have?