It would be nice to have something that took the builders wand from extra utilities and the wand of equal trade from thaumcraft, and put them in a neat little standalone. There may a couple other building tools that would be useful also, but can't think of them right now.
It is just that after you have used those two, building without them becomes much more tedious. There is the rf exchanger also, but again it is attached to another mod and requires rf to function, which might not be possible in all packs. So, something like a simple little "Builder Bits" mod or something that players can easily toss into any pack without worry of balance or compatibility or disabling everything would be nice.
It would be nice if it also added a deconstruction wand, that destroys 9 blocks of the same type at a time. It could either have a durability, not drop blocks, or blacklist stone in order to stop people from using it to mine.