Wallpaper can be the ruination of a page of good poetry. Web professionals know that tiling is an embarrassing first-generation thing to do, and don't need to read what follows. But if you're a poet who has just emerged from a HTML class where you've acquired an unstoppable urge to tile background images, please read on.
Wallpaper undermines all the good things you are trying to achieve by going online. You want to give a professional, public shape to an intensely private non-profit activity. It is so easy to make poetry look shabby, even the work of famous poets, and it is so hard to make fragile words look dignified. And then you spoil all that creativity with dumb tiled images that show you are operating a thoroughly amateur site.
Though it is hard to imagine what benefits any webmaster expects from a tiled background, I figure that wallpaper can at least provide useful signals for visitors that the site owner is a crank. To this extent, wallpaper should even be encouraged. It is like a leper's bell: it tells your visitors, "I'm a disadvantaged member of the web community. I'd decorate my home with this dorky wallpaper too, but the landlord won't let me. Don't bother to E-mail me, or I'll send you a misspelled, spacey, off-the-point reply."
Sorry folks: I'm just joking.
Seriously though: on a poetry website, all that matters are the words. The typography and graphic design should support the words. Several years ago I read with wonderment an internet page of Dorothy Parker poetry printed white on a background of olive flock wallpaper. When I looked, I asked myself, why the wallpaper? Did Parker like this wallpaper? Or was Parker into graffiti? Or was this some comment on Parker's style? The wallpaper was not grossly ugly, but it was a distraction. Wouldn't a plain coloured background have been enough? Fortunately, that site and others of the type have largely vanished from the web.