If you like Hammerfall, the lead singer also has a solo album (called Cans) and former guitarist Stefan Elmgren has a side project called Full Strike.
Other bands I haven't seen mentioned yet that fit this category include:
- Paragon, Metalium, Virgin Steele, Avantasia, Armored Saint, Arthemis, Bal Sagoth, Bloodbound, Cage, Children of Bodom, Cryonic Temple, Dark Moor, Cydonia, Domine, Doomsword, Dragonhammer, Dragonland, Dreamland, Dungeon, Edenbridge, Falconer, Firewind, Freedom Call, Gamma Ray, Grave Digger, Heavenly, Hyperion, Iron Savior, Jag Panzer, Kamelot, Labyrinth, Luca Turilli, Majesty, Messiah's Kiss, Aska, Arch Enemy, Evergrey, Lost Horizon, Mercenary, Pagan's Mind, Tad Morose, Morifade, Powergod, Primal Fear, Pyramaze, Thunderstone, Rebellion, Stratovarius, Persuader, Twilightning, Savage Circus, Ayreon (and Star One), Mob Rules, Conquest of Steel, Mystic Prophecy, Threshold, Black Majesty, Nocturnal Rites, Omen, Oratory, Pegazus, Powerquest, Powerwolf, Rage, Riot, Sacred Steel, Seven Witches, Sinergy, Stormwarrior, Symphorce, Thy Majestie, White Skull, Wizard.
Loads more but that's just a quick trawl through my playlists