David Meadows tweeted Berlin-Kent Ostia Excavations, a nice blog, whence I got to this extensive and very active site:
Ostia, Harbour City of Ancient Rome (Ostia antica)
This website is dedicated to Ostia, the harbour city of ancient Rome. Here you will find information for professional archaeologists and historians, for students of Roman archaeology and history, and for interested lay-people. The site is maintained by the Internet Group Ostia.
There are lots of things to explore, from the introduction with time line, history and maps to ancient texts, an amazing topographical dictionary, computer reconstructions, virtual museum, videos, Yahoo group, and more.