Most of my clients are great. Here is a profile list I've written for those that aren't so great.
Father Time: The client who emails you three days into a project to ask if you have anything to show them, despite telling them in advance that a sample won't be ready for several weeks.
Lemonade Maker: Any client that pushes for new ways to have features added while trying to avoid having their quote adjusted.
The Procrastinator: The client that holds up project development for unreasonable amounts of time over a single photo or bit of content that they never get around to providing.
The Googler: The client that wants to know why they aren't showing up for any Google organic searches the day after their site launches.
The Kamikaze: The client that absolutely insists on horrid color schemes or graphic ideas that totally distract visitors, despite you putting in your two cents.
The Fantasy: A prospective client that mentions their budget is only $200, and begins by telling you that "they don't want a lot of flash animation"
The Busy Expert: "I could do the website myself, but..."
The Lawn Gnome: The client who insists that hit counters, "under construction" clipart and talking virtual host flash is exactly what the site needs.
The Interior Decorator: The client that logs in without telling you, and defaces your work with fonts and pictures that aren't web-ready.
I'm Not So Sure: The prospective client that wants a complete mockup of the entire site before deciding to do business.
Phone Man: The client who insists on calling several times a day. This client also won't review the site until he can get you on the phone and make you wait so he can look at it.
The Bad Bluffer: Any client who attempts to acquire their hosting access information while refusing to indicate why.
The Picasso: Clients who insist on taking a screen shot of any work done and "improving" it with their own horrendous graphics done in Windows Paint.
The Bob Barker: The Client who doesn't have any cash, but has a great idea, and will allow you to share in the earnings if you design his site.
Captain Optimism: The client who wants you to register cool.com. He typed the address into his browser, and no site was there, so it obviously must be available.
The Bigshot: Clients that spend a week talking about a 5k budget, but decide that they'll start off with a $300 site.