Simpedia: The Sims 2: Ultimate Collection
This is the complete collection of all the Sims 2 games (base game, expansions and stuff packs). It's only available through Origin.
EA removed all the separate expansion packs and stuff packs from Origin, and instead added one listing called The Sims 2: Ultimate Collection.
Halfway through July 2014 people were able to add this entire collection for free on their accounts. You could temporarily redeem the collection by using the code "I-LOVE-THE-SIMS" which worked until the end of July, 2014.
After this promotion was over, people still occasionnally received the collection via the Origin helpdesk, when they could prove they had all (or at least some) of the original games.
There is also a similar version on Mac, called The Sims 2: Super Collection. This Mac version isn't free though, and it isn't available through Origin itself. You have to purchase it via the Mac App store.