In my deck (5cStax), I run 2x Shaman, 3x Welder, Karn, Triskelion, and Sundering Titan. I try to run creatures that force the lock (I like Platinum, but she's pretty much just there to save your a$$).
Shamans are great, first turn Land,Mox,Shaman,Go, destroy your Mox or Chalice or whatever.
Welders are just obvious (for Stax), so can't comment much there.
Karn is not just A house, he is THE house, he destroys Moxes, Chalice, etc, keeps equipment (which still randomly shows up) from equiping, he animates your creatures for the win, he's just all around a great guy.

Triskelion kills things, he does it well and he does it often, he sucks with a Null Rod out, but not enough for me to consider cutting him (he deals with Fish all day, especially with an active Welder out).
Last but not least, Titan is there to take over where Wasteland falls short, he can practically be an Armageddon against decks, while doing nothing against my own mana base. Couple that with the fact that he can almost entirely block Colossus, he's an easy add (and my usual target for Tinker).