I would like to see a few of the classic weapons/tools brought back, namely:

Pneumatic drill - So many times have I wanted to drill directly down but can't.

Minigun - Uzi is too weak imho

Pistol - Six shots can be used pretty strategically

Grannies - Sheep are unpredictable and jump alot :P

Priceless Ming Vase - The less dangerous, more strategic version of the banana bomb

Carpet strike - The rolling version of the Air Strike

I'm sure there are heaps more I haven't listed, but these are the ones that I miss using the most.