I like the thread idea too.
I borrowed a Killawatt from my library, so check there first before purchasing. Here's an awesome website for ballpark estimates of figuring out what is causing your power bill: http://michaelbluejay.com/electricity/howmuch.html
I have the following hooked up to a Smart Strip: Onkyo Receiver + Subwoofer & 2 speakers, BluRay Player, Wii, XBox, Computer Tower, 55" Flat Screen TV. I have determined the payback period on the Smart Strip to be 18 months.
I've also used interlibrary loan for movies that my library didn't have in their collection. They even had movies Netflix didn't have.
To hopefully turn this into a thread that sticks around - here is a good resource on cell phone deals:
I also recently discovered ting.com for cheap cell plans - not for me but might work for someone out there. It's more a la carte pricing than any other service provider I've seen. I think they use the Sprint Network.
ehealthinsurance.com for Health Insurance quotes.
Rockauto.com for car parts.
2% Cash Back on all purchases Amex Card - must have Fidelity account: http://personal.fidelity.com/products/checking/content/amex_rewards_card.shtml
Dropbox.com - back up 2GB to the cloud for free, can be used on multiple computer systems to sync across them all.
Google Music - back up your music collection for free, listen to it from the cloud.
I'll keep thinking of things I use and perhaps post later.