I know of a few, but am sure some of you other folks will know about a few of the less well known missing planes.
Ones that I can think of....
A four-engine Soviet-made Bolkhovitinov somewhere off of Barrow in 1937
Air Force C-54D Skymaster somewhere along the Alaska-Yukon border in 1950
A four-engined DC-4 somewhere near Yakutat Ak 1951
Boeing RC-135E (USAF Tail No. #62-4137) reconnaissance aircraft 30min out of Shemya in 1969
Cessna 310C with Senator Nick Begich on board after leaving Anchorage in 1972
A Socata Rallye 235GT, registered as N302RA just north of Kodiak Island in 1979
A Beach Bonanza (I think) that disappeared between Palmer AK and White Horse 2009
The missing Beaver this year near Katmai