Short answer, yes. Long answer YEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEES
Seriously, that game is amazing. And one of the reasons it is so great, is the modding community. They have been making them since day one, and are still doing it. With those tools, you can literally build the city of your dreams.
My advice to you, if you do buy the game. Make sure you get the deluxe or rush hour version. Because they add more features, and better mod support.
There are two great sites, which are an easy, convenient and moderated way to get mods for the game.
sc4devotion.com
simtropolis.com
If you do decide to go the modding route, get the Network Addon Mod, which I highly recommend. And go anywhere from there.
And again, this game is a blast, even without mods. But if you get them, this game has no limits.
EDIT: Well, someone beat me to it!