The detonation achievement (150 items detonated, I think) is a lot easier to achieve than it looks (and is probably the least useful achievement).
It seems that every object that detonates beside the object you chose (chain reaction) is added to your detonation tally. However, it also adds each object that gets burned.
Take a wide, empty area on your lot and buy about 25 of the measly little 5 simolean plants. The little potted ones, I can't remember what they are. Pack them in real tight. Once you detonate one of them, they erupt into a giant explosion of fury. It typically starts several fires, but thats what firefighters are for (call them, for your sake).
What's left is several little piles of 1 scrap and a bunch of burned plants. Once the firefighters clear out, detonate one of the leftover burned plants. BOOM again. Anything that is in the radius of the exploding plant gets added to your detonation count, even if it is just burned. It took me about two or three tries with this to get the acheivement, and all of 8 sim hours or so of pure, entertaining mayhem.
I would heartily recommend waiting for the firefighters to clear out completely before detonating again--I had a bug where one of the firefighters stayed on my lot indefinately, in one place, doing nothing. Somehow they never died of starvation, or boredom, from standing still for two weeks. Couldn't get them to move or interact, and notably no firefighters would come to my aid if I started another fire....