I know that there are a bunch of differing opinions on what makes the cut. I'd like to hear your opinions on colorless cards that you would put in every deck.

My fiancee and I have been playing some very low power EDH, but after I picked up a copy of Eternal Bargain, we're seeing a huge difference in the way the deck styles play.

Sol Ring, Sensei's Divining Top, Command Tower, Darksteel Plate if it has many creatures, darksteel ingot, Solemn Simulacrum. I'll post more if I think of them.

wurmcoil engine, lightning greaves/swiftfoot boots, oblivion stone, eldrazi to prevent mill, chromatic lantern, mimic vat, swords of any type, maze of ith, crucible of worlds, strip mine, reliquary tower, thespians stage

Thanks. I'm putting together a shopping/wish list now. Any others I should keep an eye out for?

Pretty much all forms of artifact ramp or other good artifacts. Mana Vault, Thran Dynamo, Basalt Monolith, Oblivion Stone, Lightning Greaves, Swiftfoot Boots, Rings of Brighthearth, Sculpting Steel, Gilded Lotus, Chromatic Lantern, Coalition Relic,

I was looking for lists of EDH staples the other day and bookmarked these two:

http://tappedout.net/mtg-decks/list-of-edh-staples-and-power-cards/
http://forums.mtgsalvation.com/showthread.php?t=161090

I hope they're helpful in your quest for useful colorless cards.

Here's my list of edh stuff on deckbox:
http://deckbox.org/sets/504803?

It includes the stuff in the prior post (thank you)

Hope this helps.