I'll start. Currently, I run an infinite AP build that is focused on maximizing single target DPS:
You can (in theory) channel the beam for minutes on end without running out of AP with no special equipment requirements for very large numbers. The downside, of course is the lack of AoE, but currently my Witch Doctor mate handles that part, while I whittle down the Champions or meatier mobs.
We're not in Inferno yet, so obviously I can run without Force armor (plus if it's to be nerfed, I'd rather not get used to it!). However, I switch my defensives (Nova/Crystal Armor) out for others depending on where we are - for example, slow time saves a lot of frustration in Act 2 against the bugs. Also, I drop magic weapon or sparkflint for another defensive if I need extra help living- Teleport or Blizzard, for example.