poocolator
Erudite
Simtropolis, specifically STEX (http://community.simtropolis.com/files/category/1-simcity-4/) is a great place to download all your SimCity 4 needs. The game is made much more enjoyable with community fixes and mods. Vanilla quickly becomes unpalatable. I highly recommend, as Turjan mentioned, checking out NAM (Network Addon Mod) http://community.simtropolis.com/files/file/26793-network-addon-mod-for-windows-installer/ which was actually just updated recently, in April. Anyway, be sure to check out the City Journals wherein players post screenshots and stories about their cities. Many players take the time to beautify their cities with graphical mods, etc.