Blaster Master is unusual in two ways: first, most of the action, and the upgrades, apply to a vehicle and not a person; second, areas are broken up by top-down Zelda-style sections. Other than that, it's classic Metroidvania.
The Wonder Boy series and the Adventure Island series both branched from the same game -- which most of us know as Hudson's Adventure Island on NES. Both series eventually became free-roaming: Wonder Boy with Wonder Boy III: The Dragon's Trap (available on Virtual Console both under that title and as the Turbografx-16 Dragon's Curse) and Monster World IV (never released in the US). Hudson's Metroidvania version of Adventure Island arrived in 1994, the last official Famicom release. It never made it Stateside either.
Tomba! added varied missions to its free-roaming and item-collecting gameplay, providing a unique variant to the Metroidvania genre. Also, along with Wonder Boy and Adventure Island, it's the third grass-skirt-related series to have a Metroidvania.
The two Tomba! games were the only games made by developer Whoopee Camp.
Created by one man over the course of about five years, the freeware Cave Story is one of the most beloved Metroidvania games ever.Which is why people are dying to pay Nicalis for a remake of a game they've already played to death.