Top 10 Set Mechanisms (i.e Exploding walls, etc)

[Life_Unscripted]

Okay, I don't know if this kind of subject has been brought up before, but I thought it was a good topic. What do you think are the best set mechanisms (Is there an actual name for these kinds of things?) ever devised by LEGO? All those trap doors, exploding walls, sliding doohickeys, secret panels, catapults, transforming sets, anything that moved or added to the play value. Each set had a few of them and LEGO seemed to like putting them in every set. Any opinions? Make a top 10 list if you want

[soccerkid6]

My favorite (as a kid anyways) were the transforming Alpha Team sets. I didn't buy Lego much, but those sets really made me want them. The only one I actually got was the Ice Blade, I was going to get the Tundra Tracker too. However they didn't have any at the store. So transforming vehicles are my favorite

[Athos]

I liked secret passage ways. Like the stairs in the Royal Knights Castle.

Steve

[Knight Man]

Sheriffs Lock-up has a good one http://www.peeron.com/inv/sets/6755-1, Stick the dynamite in the hole and the side of the jail pops open. ~KnightMan~