Dear Miss Snark,
Apart from absolute honesty, then, what does interest you on an unpublished fiction author's website? Do you always check out the websites (if they have them) of authors you're considering offering representation to? What kind of information do you (or an editor) like to see there? Blurbs of completed works? A hint of personality so that you can guess whether or not they'd be hell on wheels to work with? Their preference of gin brand?
If someone writing me a query letter has a website, and I'm not certain of some of information in the query letter (like who published a book), I'll go look.
If someone has navigated the hoops of fire and we are in discussion about representation, I check it out for two reasons: find out if it's any good (and thus doesn't need a huge makeover before editors start doing what I'm doing now) and to get a sense of their personality.
I've never turned someone down cause they had a lousy website. I've run screaming into the night when I saw websites full of wild ass political invective that seems ill thought out and hostile. You don't have to share my political beliefs but you have to write well about what you think.
And of course anyone who has a long blog about how horrible agents are gets a pass.
It's not required that you tell a prospective agent you have a website. if you've got one full of pictures of puppies and balloons and darling little foo foo bunnies, and your poems from sixth grade, it's perfectly ok to never mention it. Ever.
In fact, if you aren't published, you don't have much to put up there unless you're posting your work. I never read that stuff on a website. I have enough slush right here to keep New York's Strongest busy for quite some time.