Is there a site or something that lists all the cards available in the expansion packs and shows how many of each card is in each pack?

I usually use the online deckbuilder for that sort of thing:

http://www.cardgamedb.com/index.php/CoC/cocdeckbuilder.html

There's another downloadable deckbuilder here:

http://eric.minet.free.fr/cocbuilder/dbdownl_en.htm

I think there are Excel card lists on boardgamegeek.com but I haven't really looked - it's easier for me to use the deckbuilders. You'd start here:

http://boardgamegeek.com/boardgame/40270/call-of-cthulhu-the-card-game

And then go to each expansion's page.

Either CardgameDB or CthulhuDabbler are the quickest and best sources for online reference perusal. (I like Dabbler for quickest card searches and CardgameDB for the awesome deckbuilder, forums, and spoiler lists.)

Offline, Nyarlzabec's stuff is compulsory.