Here is the list of worlds shipped with The Sims 3 base game and expansion packs, as well as worlds downloadable from Store. Click each world name to see list of lots and download Sims3Pack world files. In total there are 23 worlds with 1845 lots and 499 families:
Shipped with game: Sunset Valley, Twinbrook, Bridgeport, Appaloosa Plains, Starlight Shores, Moonlight Falls, Isla Paradiso. Sub-worlds: Shang Simla, Champs Les Sims, Al Simhara, Sims University, Oasis Landing. Download-able: Riverview, Barnacle Bay, Hidden Springs, Lunar Lakes, Lucky Palms, Sunlit Tides, Monte Vista, Aurora Skies, Dragon Valley, Midnight Hollow, Roaring Heights.