DTWiD - Lost Episodes
Here you have a massive (6-episode!) vanilla-compatible collection of map submissions to Doom the Way Id Did. Don't think of this as just an "overflow pack" -- there are tons of super-solid maps here that may have not be the most id-like but still stand on their own as great maps. If you enjoyed DTWID and are itching for more, or if you like Classic Doom in the slightest, look no further! More information including the download can be found over at Doomworld.