Before we start:

- the official Sims 2 web site:
let's first stop by the official site. Official downloads and the exchange can be found there.

- the ModTheSims2 forum:
Your n°2 stop: great custom content and must have mods for your game. You'll find some great tutorials too. And the forum is full of nice people who are willing to help you out!
Other downloads forums: the InSIMenator, the Sims Resource.

And now to the rest of the goodies

Sim movies

Sim stories

Furnitures

genetics

clothes

lots

Finds sites, WCIF? and CC lists

(links are divided into sub-categories. Which doesn't mean that they are limited to one, ie if I categorized a site under furniture,
it might also offer genetics or clothes, it's just that my favorite stuff to download on this site is furnitures)

And if you want to link to me: