Dead Cyborg has the heart of a text adventure within the body of a 3d engine (youtube trailer). Caveats: donationware - future episodes dependent on donations. burster plug-in required for browser play
Hetherdale is a full scale point and click adventure, for free. Don't forget to use the map option when it arrives in order to travel faster.
ElfQuest for free...gradually. The complete ElfQuest comic oeuvre (about 6000 pages) is being released online in batches every friday. The first five issues (a complete 150 page arc in itself), along with some other EQ series's first issues, are already up.
AOL launches in2tv. Why pay for Lost when you can be watching Wonder Woman for free? Maybe because you own a mac or hate streaming media. (Ok, so it's probably all over teh interwebs by now - but hey - free Wonder Woman!)