Green IT has been a buzzy phrase lately for corporations looking to reduce costs and look environmentally-responsible. This may be the most attention IT has gotten since the e-mail server went down that one time, for like an entire day. To sum up this new trend, InfoWorld has announced its inaugural Green 15, a collection of the organizations with the most efficient networks and energy-hacked stacks.

The chosen few range from big names like Verizon and IBM to who-woulda-knowns like Miami-Dade Public Schools. One, British broadband provider BT Group found itself using a full 1% of the U.K.'s total power consumption. To reduce their mammoth carbon footprint, the company overhauled their networks anddatacenters, knocked out walls for ventilation and started cooling their hard-working servers with chilly British air. Since BT started the 21st Century Network Data Center Project in 2004, they have saved $7.4 million in electricity costs and reduced their U.K. carbon footprint by 60%.

Digital Realty Trust, a tech-focused realty firm started its green IT project with the hardware around the hardware. They managed to renovate a 90 year-old printing plant in Chicago, making it into the firstLEED Gold datacenter . They achieved the do-over at the request of an unnamed client. Precise energy measurements and reuse of the existing structure helped to achieve the U.S. Green Building Council's 2nd highest certification while increasing the cost of the project just 4%.

Among the other geeky greens are the cheap and super-efficient One Laptop Per Child venture and Fujitu's foray into hydrogen power. InfoWorld also finds key lessons that can be learned from these ahead of the curve companies:

1. Many green IT projects pay for themselves. 

2. Green IT isn't just for the enterprise. 

3. Green IT isn't just for the datacenter. 

4. Measurement tools are critical to green-tech success. 

5. Green IT requires input from outside the IT department.

6. Clean energy is a complement to green tech.