NFT (Non Fungible Tokens) are collectable and "play to earn" digital assets that can be land, characters, weapons, tools, etc. that allow you to earn (you get the game utility which can then be sold in dollars or used to progress in the game).
However, NFTs can also be staking, generating a passive income without practically doing anything. Let's see the main sites.
Mainly NFTs that can be staking are all those operating on the Wax blockchain (EOS sidechain).
What is needed? The wallet: Wallet (Wax)
This is the main market for buying NFT: AtomicHub (Wax Wallet)
Here you can buy most of the collections that operate on Wax. Everything is quite intuitive with the collections on the left and the "buy" button to buy or the "list on market" button to sell it.
Remember that the Wax address ends with the extension .wam (you will be assigned an address as soon as you create the wallet). This wallet is of the Metamask type: you can connect it to any game or dapps that uses the Wax blockchain. This instead is the dex to sell tokens (in Wax): Alcor (Wax Token Exchange)
I remember that Splinterlands cards can be rented on the official website of the game: Splinterlands
You can transfer the Wax cards to the Splinterlands game and then rent them out (if you don't play Splinterlands).
Ok let's start with the staking sites.

RPLANET
Rplanet offers staking for a wide variety of Wax-based NFTs. Accessing R-Planet is super easy - just plug in your Wax wallet. The platform automatically detects all NFTs in your wallet that are part of the supported staking collections. Here you earn the Aether token and you can also read the hourly staking (Aether / h). We find large collections such as Alien Worlds, Bitcoin Origins, UltraRare, The Horrors, Monsters Of Rap, etc
Site: RPlanet

WHENSTAKING
WhenStaking is from HodlGod company, one of the most popular blockchain games. Whenstaking.com allows you to see the NFT assets of other Wax-based games. However, only Onessus-based NFTs can be wagered. To use whenstaking.com, you will need a Wax wallet. Once logged in, you will be able to view your dashboard and all NFTs in your collection. Once you have chosen which NFT to stake (by going to "filter by" and "all stakable"), a popup will appear asking you for the desired blocking period. The window also calculates the APR percentage you will get for the specified time period, you earn Void tokens. In addition to NFT, you can also stake Void.

COINPIRATES
This site called Coinpirates is quite basic in its functions. Here too it is a game. Not many NFT are supported, apart from those from Kolobok, Rplanet and two collections from CoinPirates itself. In this case they earn their CPR token which can be sold on Alcor. Site: Coinpirates

WAXARENA
With Waxarena our NFT will not leave the wallet. They generate passive income in the AEXP token simply by holding it in the wallet. A flaw is that it is possible to sell the token once the payout of 1000 AEXP is reached. With AEXP (which obviously can be sold on Alcor) it is also possible to buy equipment and upgrades for the game (play to earn arena fights, of course). Passive income is unlocked by accumulating Power Points (the hourly reward from 500 upwards is unlocked and then the next one from 100 to 100, continuously increasing the cards to be staking). Site: WaxArena

KOGS
Interestingly, in addition to serving in the game, KOG can also be staking. Like most Wax-based platforms, Kogs allows users to log in with their Wax account. The platform therefore recognizes all users' NFT, allowing staking. If you stake an NFT and it is locked for 90 days, you will receive a fixed rate of RFOX tokens. Site: Kogs

VULCANVERSE
VulcanVerse is based on the Vulcan Forged protocol. VulcanVerse and its native PYR token offer a great way to earn passive income. Lands in VulcanVerse can also be upgraded. However, this requires the PYR token. An improved parcel of land will give players a larger portion of the reward pool. To get hold of a Land in VulcanVerse, you need to visit the Vulcan Forged Marketplace. Site: VulcanForged

Are you interested in ways to earn crypto bonus? Check it out here (last UPDATE 04 October 2021): Some Sites To Earn Crypto Bonus (Old & New)