Easiest First Thing to 3D Print

[JamesTuthill]

What would you suggest to someone that is going to use a 3D printer for the first time, and just wants to see how it works, but at the same time print something rather interesting?

[Feign]

For a first print, you're going to want a calibration print of some sort to gague just how good your printer is at specific things.
http://www.thingiverse.com/thing:24238 is probably the most popular, and if you have problems, print this out and post pics of it, most people here can diagnose from it.
There is also, http://www.thingiverse.com/thing:9804 and http://www.thingiverse.com/thing:64549 which look kinda cool if they're done right, and will let you know very quickly if there's anything needing adjustment.

If you're feeling confident (or lucky) and want to just dive into your first neat trinket to show off though there's the Nautilus Gear, which is pretty impressive for such a simple print:
The original: http://www.thingiverse.com/thing:27233
And a very nice looking variation: http://www.thingiverse.com/thing:258201

[oklok]

Feign , you should make your post sticky. I think most new to 3D printing would appreciate the post you just wrote.

[Feign]

To be honest, it was just a few minutes of searching "test print" or "calibration" on Thingiverse.
What I used on campus and at work were the 3D Kitbash test chips, very complete and very thorough (and they look good enough to display with your printer) but they aren't free. When I have my own printer, I might buy the 3DKB Graphica pack to print for the bragging rights, but those are specifically intended to be challenging.

I'm one of those very strange people who will actually pay money for a 3D model if I like it enough, and I recognize I'm in the minority there.