There is now a thread at the official Sims 3 forum which lists links to many fansites with Custom Content. I urge you to view it for the latest updates.
I’ve been dropping the ball when it comes to posting Sims 3 modding-related news. A number of sites have already broken the custom-content barrier and are now providing custom clothing, patterns, hair meshes and tweaks to the games (objects are coming, but need more time). Thanks to Sims 3 Nieuws, they’ve directed me to a post by SimGuruHydra containing a few CC links:
Simmers are really quick to find great CC from these sites:
and many others…!
And for those who are looking for new hair styles, I urge you to check this webpage out.