The Wordwood. That is, the original Wordwood as thought out by Charles De Lint.
To begin with, this was a literary online database, created by Holly Rue and friends, hosted on an ordinary web server.
After a couple of years, the Wordwood came virtually alive: it apparently edits itself (although we know that's not really the case - see Spirits In The Wires); it replies to emails; it is no longer hosted on any real life webserver; it shows a real time video of a forest in the Otherworld?; it speaks to everybody in a different voice;
Mentioned in a heck of a lot of stories and novels - too many for me to even begin listing them - but feel free to edit this page whenever you come across a reference!