The world loves Wikipedia, flocks to Flickr, and listens to Last.fm. And why not? Web 2.0 sites like them harness collective knowledge, promote interaction and communication, and improve the more you use them.

Alas, not every Web 2.0 site is a winner. Many are vague, pointless, or just plain silly. As Web critic Nicholas Carr notes, "If I were called in to rename Web 2.0, I think I'd call it Gilligan's Web," after the goofy '60s sitcom.

How do you identify a dumb Web 2.0 site? First, the site's mission statement must be impenetrable. ("Spotback is a personalized rating system that recommends relevant content based on personal rating history using collaborative filtering and aggregated knowledge technologies." Huh?) Second, the site must solve a problem that has been solved a million times already or didn't need solving in the first place. Third, its name must love the letter "r" but eschew vowels ( Drivl, Grazr, Hngry), or be a refugee from "Jabberwocky" ( CurdBee, Egghub, Humyo, Jiffle).

Here are 14 of the silliest and most redundant, tasteless, or mystifying Web 2.0 sites. Warning: Visiting these sites may impair higher brain functions.

Blabberize

If you were a venture capitalist and some supposed Web visionaries came to you with a home page dominated by an animated picture of a talking alpaca, wouldn't that in itself be enough to make you say "No thanks"? Apparently not in the case of Blabberize, which lets users add audio and animate the mouths in pictures, like this take on Jack Ruby shooting Lee Harvey Oswald. Now that's comedy!

BillMonk

Let's say Dan owes you $20 for pizza. You ask Dan for the money. "Robert," says Dan testily, "I paid for your botox last month, remember? Chill." D'oh! How embarrassing. If you were using BillMonk--"a free service that makes it easy to track expenses between friends, and to settle them up instantly online"--you wouldn't be in this fix. According to its creators, BillMonk is particularly popular with roommates, college students, and other folks who can't communicate via vocal cords or sticky notes.

Blippr

The Short Attention Span Theater isn't gone--it just moved to the Web. Blippr, for example, lets you review movies, books, games, and so on, in 160 characters or less. This setup results in such trenchant appraisals as "Some ginger dude eats macdonalds every day until he gets fat and chunders" ("Super Size Me") and "this is a fine specimen of bookage" ("The Hitchhiker's Guide to the Galaxy").

FoodFeed

"Ate McDonald's every day until I got fat and chundered." Don't keep such morsels to yourself. Thanks to FoodFeed, you
can share your eating habits with the world! Legarvin in Fort Lauderdale had a cheese stick 41 minutes ago. Maurawani in Vienna just wolfed down some "scholle müllerin, karotten und kartoffelpü". Mein Gott!

Yay Hooray

I once wrote about the most boring Web site in the world--a single page that listed the latitude and longitude of every stop sign in my county. I may have found a topper: .Yay Hooray, which seems to be an online watering hole where people network about, um, nothing. Think of it as a "Seinfeld" episode without the laughs. Killer discussion threads include "What are you listening to RIGHT THIS SECOND??" "DO-NOT-EAT-PRINGLES-FAT-FREE-POTATO-CHIPS.-THEY-WILL-GREASE-YOUR-ASS," and, of course, "i am my own doctor." The membership sign-up box says it all: "Wanna join up? Tell us why!"

Denodo

In the words of one Web-development god, this site is FBC--Fully Buzzword Compliant. A sample: "The Denodo Data Mashup is a highly innovative architecture that enables the agile creation of new services by integrating existing data from all kind of sources (not only structured and internal data, but also unstructured or semistructured content on the Internet)." Totally monetizable!

Greedy or Needy

Like any good reality show, Greedy or Needy brings out the very best in human nature: greed and groveling. State your pathetic greedy desire ("I love Turtles and Sherri has one I MUST have!") or needy wish ("I don't have any [dryer] balls"). Everyone votes, and two "winners" receive $100 apiece--which, we hope, they'll use to buy a life.

Predictify

Exercise your inner Nostradamus. At Predictify, you don't just read the news--you predict it! If you're accurate, you can earn real money. But who's coughing up the dough? "Premium question-askers" who could be vendors, marketing firms, pollsters, or individuals who truly want to know "Will Paris Hilton's energy plan be adopted wholly or partially by Congress this year?" In typical Web 2.0 fashion, you can connect with other members, compare rankings, challenge their predictions, and so on. The convoluted rules, however, may send you running back to Greedy or Needy.

Yubnub

Let's say you're looking for pictures of a Porsche 911. The antiquated, Web 1.0 way would be to click Google's Images link and type "porsche 911". But what a hassle! In the brave new world of Web 2.0, you go to YubNub and type "gim porsche 911". See how much easier that is? Why go all over the Web when you can do everything in Yubnub--provided, of course, that you can remember dozens and dozens of arcane codes. The coolest part? Yubnub may someday let you link different Web services, so you could, say, automatically convert Web-page text into audio. Just be prepared to master syntax like "google jon udell | to_rss | xargs text_to_speech".

Savvy Auntie

Go to Google and type "social network +" along with your biggest obsession (fudge, cats, Tupperware), and you'll probably find a social network just for you. How niche do things get? Consider Savvy Auntie, a network for women who desperately need tips on being an aunt or grandmother. (Apparently, having relatives who procreate isn't enough.) Here you learn how to sing "Itsy Bitsy Spider" (in case you've forgotten the lyrics) or how to throw a "High School Musical" theme party. You can also tap into Auntiepedia, a wiki that boasted two postings when I checked. Uncles need not apply, as they are superfluous.

File-swap.com

File-swap.com is the ultimate black-box interactive Web 2.0 experience. Upload a file to the site, and you'll receive a random file from another user. Have a TIFF of your divorce papers? A slide from your vacation at the Pismo Beach Snail Ranch? Upload away! You just might get this fine piece of portraiture in return.

Plurk.com

Experts we polled agree: Plurk.com could be the shallowest site on the Web. It isn't just another clueless social network. This Twitter wannabe takes the "deep introspection required out of blogging" (say what?) and gives you entrée to "instant gratification, instant celebrity, instantly YOU...Plurk!" Yurk! (And if Plurk isn't enough for you, there's also Plurkaholics, Plurkular, and Plurkland.)

BarbieGirls

Want to raise a good little Web 2.0 consumer? BarbieGirls.com is the place for your princess to log in and get down. With the free account, she can design her virtual character, decorate her room, chat with new friends, and visit their rooms. But step up to VIP membership ($6 per month), and we're into amassing virtual purses and jewelry, sending gifts, staging a fashion show, getting a special tiara and hairstyle, and, of course, earning Barbie-bucks. If you're raising a future Zsa Zsa or Paris, go no further.

Profilactic.com

Not only is the name yucky, it bears no relation to the site's purpose. You'd expect Profilactic.com to, um, hold stuff in. In reality, this "social media aggregator" is an information toxicity generator. With a few clicks, the site grabs everything "you and your friends create online...from 186 sites by default." In my test, Profilactic spewed pages and pages of online nattering, photos, and other digital detritus that my friends and I had posted in moments of weakness. My advice? Forget data aggregation--and find friends who can't type.