Back on topic, as Vulpes wished - no, I don't ever put them on my computers. I have had them from everything - my Athlon 64 3500+, my EVGA GeForce 6800 GT, my BFG Tech GeForce 8800GTOC, my Phenom II X4, and my EVGA GeForce 560 Ti SC. And they're all dumb looking. Especially on custom builds. Whether they're a tiny sticker or a larger plastic stick-on, there is seldom a good spot for them on a custom build, save for maybe the side or the back. And then, who is ever gonna see it? I just built a rig for a friend's sister with one of the AMD FX quad cores in it, asked her if she wanted it on. She didn't and it promptly went in the garbage pile.
I DID put one of the EVGA stickers from my 6800 GT on the back of my old Cooler Master case. I regretted it, because it's dumb looking, even though nobody is ever gonna see it because I am the only person who works on my computers.
So in other words, I prefer the sleek, quiet look instead of the gaudy "OMGZ I GAWTZ A PEENOM EX TOO AND MSI MOBO IN HURR" look. Though, if the 560 Ti I got came with one of the tiny stickers, I might be tempted to put that on in a bottom corner or something. Just because I am kinda conceited. I'm kinda proud that my video card costs half as much as the computers I am building for my friends. But it came with a big, hard plastic emblem thing. But who is ever gonna be inspecting the bezel of my tower except me.