gratuitous animation
With animations you get the all the wonderful injuries of the blink tag with the added insult of the graphics download time. People who abuse these should have flip books rammed into every bodily orifice until they figure out that a two- or three-frame graphics loop is even less pleasant than that.

rish backgrounds
The very next time we stumble across a page composed by somebody who thinks it's cool to use leaping flames or a big moire pattern or seven shades of hot pink swirly as a background, we swear we are going to reach right through the screen and rip out that festering puke's throat. If there's a worse promoter of eyestrain and migraines than the blink tag, this is it.

large fixed-size tables
This one is often brought to you by the same idiots who so love "resize your browser to..." instructions. Hello? Hello? Would somebody explain to me how it escapes these people that the world is inhabited by lots of people with different sized displays, and that tables flow for a reason? Sigh...

masturbation with Javascript
There is a large class of Javascript annoyances perpetrated by people whose ability to do cutting and pasting exceeds their negligible sense of taste. Of these, one of the most common is the script that scrolls text in the Netscape status line. To all the disadvantages of <MARQUEE> this one adds the fact that you can't see where links go any more. Better than that, pages with 25K of Javascript followed by < 5K of actual content; these pages, of course, are invariably hosted on slow servers so you can experience the pleasure of waiting for Javascript to load just so you can see a cutesy animated menu bar or something equivalently useless. In general, any page whose source has more Javascript than content should be sent to the recycle bin.

pop-up windows
Some particularly irritating designers have discovered the magic formula that causes your browser to spawn a new window when you click on a link — or worse, ways to make pop-up windows appear even if all all you're trying to do is exit their wretched hive of scum and villainy as rapidly as you can find the Back button. Stay in your own window, dammit! The Web is supposed to be about viewer control; designers who persist in rudely grabbing pieces of the viewer's screenspace without permission deserve to be lashed with knouts.

menus made entirely from image maps
Clue: lots of people use text-only browsers like lynx, either because they want to (for speed) or because they have to (visual impairment, or lack of a graphics display). An entire page that shows up only as "[ISMAP]-[IMAGE]" is useless. Designers who can't be bothered to at least provide a link to an alternate text menu are, at the very least, guilty of laziness and thoughtlessness. Huge image-maps are bad even for graphical browsers; they're slow-loading and needlessly frustrate users. And a frustrated user is a gone user.

CSS that sets fixed-size fonts dimensioned in pixels
This is the idiot web designer's favorite way to make a site unreadable on a monitor with a finer dot pitch than the one he/she happened to use. Guess what happens when you set a 10 or 11px font on a 72dpi monitor and it gets viewed on a 120dpi monitor? That's right, instant eyestrain and another user cursing your name. This problem is going to get worse as displays get larger and finer-grained.

background MIDI, Flash, Shockwave, and other abominations
Background music takes forever to load, and isn't portable. Flash and Shockwave take forever to load, aren't portable, and are proprietary formats that lock you into a single vendor. When you insult your viewers with crap like this, don't expect them back.