Quite a few for me:

Scorpions - pretty much most albums from Lovedrive through to Savage Amusement...maybe even Crazy World.

Iron Maiden - Killers through to Seventh Son

Saxon - Wheels through to Power and the Glory

Queensryche - Rage to Empire

Manowar - Fighting the |World through to Truimph of Steel

Dio - Holy Diver to Dream Evil or if not the band then Dio where you could string Rainbow through to Sabbath through to solo!

Whitesnake - Lovehunter through to Slip of the Tongue

Europe - TFC through to Prisoners

ACDC - Highway to Hell through to For those about to Rock

Vicious Rumors - Digital Dictator through to Welcome to the Ball

Winger - ST through to Pull

House of Lords - ST through to Demons Down

Metallica - Ride through to And Justice...maybe even Black Album!

Heart - ST to Brigade (Desire Walks on is great too so could be added)

Purple - In Rock to Machine Head

Sabbath - ST through to Vol 4...maybe more too

Sabbath - Heaven and Hell to Live Evil (slight cheat there!)

Ozzy - Blizzard through to Ultimate Sin.

Megadeth - Peace Sells to Countdown

Alice Cooper - a few again maybe but will plump for Raise Your First to Hey Stoopid/Last Temptation.

Judas Priest - Screaming For Vengeance to Turbo...I am also one of the few that likes Ram it Down so that could be added along with Painkiller!

Van Halen - first three or 1984 through to F.U.C.K.

I am sure there are more - Queen would be another who have had a few strung together.