List the best tools for staying ahead!

I'm not so much a newbie, more so a longtime lurker turned poster.
As I have to go through the newbie posting process I thought I'd make my first post something that adds value and at the same time one I can learn from given other's responses : )

So, I thought it would be great for us to collate a list of all the tools/sites/repositories that help you stay up-to-date/ahead of what's going on in the world of cryptocurrencies! (exchanges unnecessary, unless they have some sort of super hidden feature)

I'll start with some of my favourites and add more as per your contributions (contributions will be credited!)
Please add: site link + one line description of use + [username]. As follows:

http://fiatleak.com/ - watch the world currencies flow into BTC in realtime [cryptox]
http://coinmarketcap.com/ - view 24hr changes in market cap for list of altcoins [cryptox]
http://www.cryptofolio.info/ - list your portfolio of altcoins and the site will add values up for you in real time [cryptox]
https://blockchain.info/ - everyone's favourite blockchain exploer, enter a BTC address and see the transactions! [cryptox]
http://bitcoinwisdom.com/ - for all you day traders out there [cryptox]
https://cex.io/calc - one of the cleanest mining payout schedule calculators [cryptox]
http://p2pool.org/ - mine altcoins, no registration required [cryptox]
http://www.cryptocoincharts.info/v2/arbitrage - useful site overall but my favourite part is the arbirtage calculator [cryptox]

Let's try and uncover those hidden gems!

Cx