I would say the lightsaber blade, but that first appeared in 1999, so I think it doesn't count...

In that case I'm going to have to go with the spyglass. It can be a spyglass, a torch, the supporting bars on a fence or a biplane or a banister, the base of a stool...

I'd also say the cheese slope, but to use it to its full potential requires inverted cheese sloped and corner cheese slopes. The double cheese slope is useful, but not as useful as any of those would have been.

Lovely as the cheese slope is, I still think Brick 1x1 with studs on two opposite sides would win it for me. Would the cheese really be quite as good without it?

We have had a 1x2 version of that brick for some time now, which in a lot of situations serve the same purpose. The cheese, on the other hand, is something fairly different from any piece before it, and yet still so useful.

No love for the Indy satchel? Or is this just for non-Minifigure parts?

Cheese slope is obviously a contender, as well as the 'scope, but allow me to point out the 1 x 1 brick with studs on 2 sides. A very useful parts.

Hmm... maybe this thread should be retitled "Elements of the decade"?

So it sounds like Cheese wedge is element of the decade and telescope could be element of the year, Congrats you two.

Maybe next decade Telescope, keep trying!

I am going to say Telescope!

Cheese seems pretty good as an element of the decade, even though it hasn't been around for half the decade.

The clicky-hinge pieces though, have been around this whole decade and have redefined LEGO hinges. I still wouldn't nominate it for element of the decade, though, since I like the old hinges better.

Perhaps the bigger cheese with grille could also be nominated as the cheese of technology, since LEGO throws that piece in so, so many sets now.

Island baseplate for me, followed by the telescope, new fire, and all the new food elements.