Simpleco.in is a nice clean website with a seperate small mining window, that lets you mine from your webbrowser. it offers bitcoin, litecoin, eth and other coin mining. simply signup and start mining.
Allcoins is another site that mines cryptonight, a monero variant, that automatically converts to bitcoin
Dogeminer is a site that mines dogecoins. Dogecoins aren't worth much, but you do get a lot of them really fast
Mining work mines for bitcoin.
