I mentioned a little while ago about a group of people getting together and doing a prequel to Portal. All original stuff leading up to the first game. Something like 400+ original lines of voice acting and such to that. Well the wait for this is now over.
As of yesterday, you are now able to download the first build of these prequel levels to the game. It is a pretty big, well relatively big, download of almost 800 MB through Fileplanet right now, but they are looking for more mirrors for download. So feel free to download and try this extra content and post a review. Mine will most likely be up in the next day or two if you want to wait to see if waiting for the download is going to be worth it. My bet is that it will be.