Dogster.com lets owners create profiles for pooches. Featuring nearly 450,000 pup pages, the site offers forums for owners to talk with one another as well as with veterinarians.

Ravelry.com has “attracted tens of thousands of knitters.” The site helps them organize projects and share designs, as well as “trade patterns, offer advice for getting through knotty problems, and critique one another’s creations.”

Birdpost.com is where birdwatchers flock to online. Avian enthusiasts can share lists of their sightings; browse birds by name, region, and physical characteristics; and locate others’ sightings on satellite maps.

Ning.com lets users create their own social networks. Whether you want to share cake recipes, unite fellow Packers fans, or obsess over The Hills, simply name your social network, pick a Web address, and invite friends.

Source: Slate.com