I haven't ever made a post here on Hive including these links, but if you're a member of the Splinterlands Telegram, you'll definitely recognize a few of these. I figured if there is anyone who hasn't joined the Telegram yet, they can hopefully find something useful here to assist with their gameplay!
Markets, Renting, etc.
Peakmonsters - offers an explorer to view any users recent transactions (reward claims, purchases, transfers, etc), an entire rental market, a bid system, and the ability to purchase through the Splinterlands market, just like in the game.
Monster Market - another way to access the Splinterlands market, with a cashback system for any purchase made with DEC.
Card Auctionz - a newer site, which I personally haven't used, but is definitely worth checking out.
Splinterlands Wiki - A great source for basic information at the moment, but it is constantly being updated, and hopefully will be the go-to for all the nerdy details we all want.
Kiokizz's Reward Card Information - a great chart, showing how many of each Reward edition card have been printed, along with a full list of all that are out-of-print.
Kiozkizz's Season Report Card - another awesome tool from Kiokizz; allows you to create a report card with your stats from the previous season. You can view how often your cards have been used, and the success rate for various summoners... all kinds of awesome info to help you improve your gameplay.
Hive Engine - the go-to for trading DEC on Hive; lots of other tokens available.
Tron Trade - as the name suggests, a DEX for DEC - TRX. Using Tronlink in browser is the easiest way to access it.
Cryptex24 - an exchange where you can trade Hive DEC for BTC, C24 (their token), and USDT.
Uniswap - You can trade DEC for ETH here, and participate in their defi pools. There is a new pair from Uniswap also, DEC-DAI.
Splinterlands Discord - Don't forgot, along with the Telegram channel, we have Discord with quite a few users, so definitely check that out. There are channels for buying/selling, how-to-guides, etc.