Since old topic is dead and full of useless junk which only pushes newcomers away:

            REBORN

  Only useful ones edition

All these services will be useful for both beginners and experienced traders.
I used all of these and still use many of them.

Since i can't post pictures  , you can check visual overview here: https://imgur.com/a/Bj5nv4g

https://coinmarketcap.com/ - Yeah, this is coinmarketcap. Coins overview, stats, portfolio.

https://cryptowatch.net/ - Many TradingView charts at one page. You can track all your goodies at same time

https://datamish.com/ - Longs vs Shorts. Often, when making a decision, I start from these statistics.

https://bitcoin.clarkmoody.com/ - Bitcoin Tickers from popular exchanges on one chart.

https://blockchainwhispers.com/bitmex-position-calculator/ - Bitmex Longs vs Shorts. Most useful for Bitmex traders, obviously.

https://aggr.trade/ - Futures aggregator. Live cryptocurrency trades visualizer. Must have for futures traders.
https://chrome.google.com/webstore/detail/aggrtrade/dachmjaingllkdmljlfhaphbflehijab - Compact version for Chrome.

https://www.tensorcharts.com/  - Charts with heat map. Sometimes you can predict price levels with it.

https://data.bitcoinity.org/markets/books/USD - Combined order book. With order book depth you can also predict price levels.

https://www.coingecko.com/ - Coinmarketcap alternative. Usually you can find new coins here before coinmarketcap listing.

http://coinmarketcal.com/ - A website that list upcoming or past events about cryptocurrency.

https://whale-alert.io/alerts - Live tracking of large crypto transactions from and to exchanges. Whales now smarter than before, but yeah

https://tradinglite.com/ - Awesome heat maps. Just love it.

https://coin360.com/ - Quick market overview. This is the first website I open after waking up.


That's all I could recommend.
I don't think I'm missing anything, but if you know any good tools, I'll be happy to add them to this list.