Ethereum keys

This website contains a sequential database of all Ethereum private keys, spread out on pages of 128 keys each.
The key to every wallet, including Vitalik Buterin's wallet, are hidden in one of the pages.

Ethereum wallets can also contain altcoins. This means you can also find ChainLink, OmiseGO or any of your other favorite altcoins on these pages.

Import/Export keys

A simple way to import or export private key from metamask wallet.
Please refer to the instructions below
How to import an Account
How to export an account's private key

You could also start on the first page and work your way up.

Search

You can find out exactly which page an Ethereum wallet is on by searching for the private key.