Reader Aaron keeps his computer on for easy remote access and for nightly scheduled tasks (like backups and defrags), but didn't want to waste the energy an always-on computer would. So he hacked together a network setup that uses power-saving settings and Wake on LAN technology to get both energy efficiency AND constant availability. He estimates this new setup saves him almost $200 a year in energy bills and reduces his carbon emissions by 234lbs (!!). Here's how he did it:

I used the open source DD-WRT firmware to set up a wireless bridge between my access point and my PC which is in another room. That allowed me to use Wake On LAN (WOL) to power up my computer remotely. I then changed the settings in my computer's BIOS and in Windows to allow WOL to start my computer from whatever state it was in. Lastly I used a BIOS setting to power my computer on every night at 3AM for scheduled maintenance tasks.