Recently hostgator went green, probably making them the first main stream host to do so. They purchase renewable energy credits up to 130% of their total power consumption.

Hostgator offers linux hosting only(even though they are expected to start windows hosting in the near future). All their packages come with all the features needed for a serious website. Baby and Swamp packages allow unlimited domains(add on), which makes a lot of sense if you have multiple websites. They use cPanel, which is the best control panel around. You get Fantastico script installer which will install most of the popular open source scripts with few clicks.

They support PHP4 & 5, SSH, Cron jobs, Python, Ruby On Rails etc. Also, all the packages include enough POP3 accounts(20 for Hatchling and unlimited for others).

Hostgator host their sites on top-of-the-line Dual Xeon servers in their data centers (thePlanet) at Dallas. The data centers are well equipped and connects to 10 backbone providers. They offer 99.9% uptime Guarantee which is the industry standard.