1. “Real World” Interfaces.
Yeah, the menu should totally be on a banner pulled behind an airplane. Get it? It’s a “fly out.”
Leave the real world to the real world. To borrow from Clement Greenburg, “screen is screen, pixels are pixels.” You’ve got a million colors and several million pixels to play with, unlimited fonts, and the only thing you can think of is a coffee table? But the telephone links to “contact us.” Get it? Apple pioneered this interface in 1995, and your idea is neither new nor interesting. Try again.
2. No more popups. Seriously.
And do NOT expand the browser window with javascript to fill my entire screen. Likewise, do not shake it, wiggle it, or otherwise manipulate it beyond changing the content within the browser window. It is my browser, and I have it just how I want it. I am graciously giving you my attention for a few seconds, and if you so much as twitch the screen, I will leave because you have broached my personal space.
3. Buck Conventions.
Like it or not, some web design conventions have emerged over the years, and your mom is just starting to get the hang of it. Search boxes go up at the top right. Navigation on either the left or across the top. And it does not move from page to page, or when your mouse gets close to it. Text links are underlined. Unless you are prepared to retrain my mom, your mom, his mom, her mom, and the millions of other web users who have learned to follow these established conventions, do not break the rules, unless you have a very, very good reason. And no, that reason can’t be “it looks better.” Or “it won’t fit over there.” Make it work.
4. The Filter is the Message.
Just knock it off. Lens flare does not a design make. People who design realtor’s web sites seem especially prone to this. TIP: For an *instant* realty web site, open your realtor’s portrait or house photograph in Photoshop. Play the default action called “Quadrant Colors.” WOW!

5. The Helvetica Goes Up to 11.
Helvetica is an awesome font. Used for your headlines, body text, logo, tagline, bylines, fishing lines, captions, pull quotes, it is boring. It has been used to death by the Web 2.0 crowd, and if I see another all-Helvetica site I will probably look up your house on whois.sc and Google Maps and sign you up for lots of spam and laugh at how tiny your hard drive looks from 100,000 feet.
6. Idiot Quotes.
As opposed to ’smart quotes.’ Even Microsoft Word knows better than to use vertical quotes in setting text. I will forgive you not doing this in HTML text, but when you are using an image for a headline, it’s inexcusable.

On a Mac, get a curly quote with:
option + shift + ]
On a PC, visit Apple.com and order yourself a Mac. On a Linux box, get a real job.
7. Comic Sans.
Greater minds than mine have addressed this serious issue, but with the frequency I seem to encounter it, I think it bears repeating.