Valid point there Orgg, but the problem is that its only good against people playing a weenie deck or something...
Still, nice idea though... especially if you try teaming it up with a March of the Machines or something to get your indestructables ready for war.
The Orb though... well... Sure you can use the blue tapping thing... but its not really as economical. Example:
Twiddle: tap one land to tap an opponents whatever. Eye for an eye trade off.
Aboshan, Cephalid Emperor: Four or more tapped permanents to tap whatever nonflyers your opponent plays (And if your opponent is an old school player, your not likely to have more than 3-4 creatures out on his side of the field)
Choking Tethers: tap four lands to tap up to four opponents creatures... if they have 4.
Etc. etc. etc....
I don't really see it very economical in any sense... Still... if you use a card like Feldon's Cane or something at the right time (assuming you have taken care of opponents creatures and spells somehow during the game) you can easily get a card advantage on them... But other than that, what can you do? Play Necropotence and pray?