Minecraft – In MineCraft PC, how do you make a permanent name tag

I highly recommend Etho's excellent subterranean spawning pads with a water-based mobevator for moving mobs to the surface. An ammended tutorial for the mob-spawner and transporter can be found here.

The video doesn't include a mob-killing mechanism but there are multiple examples on his youtube channel. Personally I prefer transporting them a bit to the side of the mobevator, then leading them up a 2x2x4 tube of water with signs creating a gap one tile up from the ground. The mobs swim to the top and drown in the enclosed 2x2x2 cube of water, while their drops fall through the gap and into the bottom 2x2x1 water stream that you can channel wherever you want to.

[Edit: I forgot to address your requirements.]

Easy to build? It requires nothing but pickaxes and a bucket. Glass makes it easier to construct but isn't necessary.

Completely reliable? I have never seen a clog, ever, nor has it ever failed to kill a mob.

Good item-gathering? 100% recovered drops, no lava or cacti to destroy them and you can channel them to a single tile anywhere you want with the output water stream.

There is a mod that will do this for Every block in the game and is compatible with quite a few other mods.. it is oddly enough called WAILA or What Am I Looking At.

There is however no way to do this with out modding the game. It is not part of the default game like the scoreboards and such are.