There's Disciples III Reincarnation. It's basically a complete pack including Renaissance and Resurrection as well as several other game balance fixes. It was released primarily in Russia, but has an English version that is being sold digitally in select placed. It is considered by many to be the definitive edition of Disciples III.
Another one would be Arcanum: The Lost Dungeon of Souls. It's a special module for the game that was included on a bonus disk for people that pre-ordered the game.
Earth 2140's release on steam contains a version of the game that supports hd full screen resolutions in contrast to GOG's Dos version. The problems with the game's AI are apparently still present in both last I checked.
Another not very well known game is Die Siedler – Aufbruch der Kulturen (The Settlers). Released only in Germany, inbetween Rise of an Empire and Settlers Seven, the game has also had it's multiplayer servers shut off by Ubisoft, however there's still a functioning singleplayer mode if I'm not mistaken.
I don't know who'd want to play these, do to their age, but there is the Exile series 1-3 which could be considered part of or successors to the Avernum series. They are however incredibly dated and available as freeware on Spiderweb Software's website.
Post edited December 27, 2013 by SunkenPlatypus