Hotseat games!? those don't exist anymore! (I assume by "HOMM" you include the sequels such as HOMM:V. you specified other sequels)
List of not mentioned Hotseat games:
Bionic Commando: Rearmed (kinda need a controller if you are playing the PC version, because 2 people at 1 keyboard is a little combersome)
Virtually any chess program
Cities3D (kinda, its a poor implementation)
wow.... I really can't think of much else. I assume you mean 'on PC' since the list gets considerably longer if you include PS3/Xbox/Wii games. This means I NEED to make a hotseat game at some point.
(Bionic commando: Re-armed is awesome because the Boss AI changes if you are playing 2 player)