I'd like to add some more links to that,
http://coinmarketcal.com/ - lists all upcoming events, and is community driven -- ( say an event gets cancelled/isn't going to happen, by enough votes it will actually be removed and vice versa.)
I also follow a wide variety of crypto-related users on twitter, who tend to tweet about big happenings/events. Might be something you want to do aswell.
http://airdropalert.com/ - not sure if it lists 100% of all the airdrops, but a quick look could give you some free coins. (Be wary when downloading wallets for said airdrop!)
