MoneroMilk is a XMR mining pool. It has a 1.2% fee (of which 0.2% is donated to the Monero core dev team) and runs on a Prop distribution method. The payout is set at 0.35 XMR.
Black Arrow Software has a range of products across the hardware space for crypto currencies. It's original push was for Bitcoin ASIC's with it's Minion Chip. It soon expanded into Litecoin ASICS with the Minion2 chip. Although its chip bundles are prohibitively expensive for most as they are large bulk orders - there are options to buy in smaller quantities.
The Company does produce a mining rig range - the Prospero X-1 and the Prospero X-3 - although pricing has to determined by contacting the Company.
Furthermore the Company has just introduced its own hardware wallet - the eWallet.
Solo.CKPool is a solo mining pool with a 1% fee for BTC. CKPool allows users to mine solo without downloading the blockchain or running a node, which means users get 99% of the full bitcoin block reward (12,5 BTC).
Obelisk is a wholly-owned subsidiary of Nebulous, Inc., the company behind the creation of Sia, a blockchain-based storage network that operates on top of a decentralized market.
The Obelisk company focuses on building mining equipment for the SiaCoin, a Blake2b-based cryptocurrency. So far, the company has released one ASIC miners dubbed Obelisk SC1.