Weather Pixie, a personalized pixel weather companion
Most weather sites give you easy options for adding weather to your site using some stock weather "stickers" they make available for you. Usually it's a pre-packaged piece of code they put together to simply cut and paste. You can choose the city and the type of information you want to show. It serves both parties pretty well as it adds content to your website while providing free advertising for them. Some sites that offer them include, Weather Underground (someone needs to hire them a designer, they are fugly!), the Weather Channel, and if you look hard enough you can find the offerings of Intellicast. There are plenty of others too so feel free to post them in the comments.

Gothamist is most intrigued by the offerings of Weather Pixie. It's fun, geeky, informative, and all with a hint of bizarreness which makes it somewhat addictive. According to their own description:

The WeatherPixie is a little graphic that shows a representation of the weather using data reported (mostly) by airports and aerodromes around the world.

As the weather in a particular location changes, the characters clothes will reflect the weather and the graphic will show rain, snow, airborne particles and changes in cloud cover. Daylight, sunset and current moon phase are also displayed.

There are a number of characters to choose from, all reminiscent of 80's video game characters. You can even meet them all, see all of their outfits and learn who they are supposed to be. Gothamist wonders at the striking resemblance of WeatherGirl:10 to Michael Jackson but personally we like the random setting so that someone new is greeting you every visit. The data is taken from local metar data in the area and is usually about an hour or so behind.

We'd like to see some local characters for this one, like The Donald or the cabbie (this one would ask you whether you knew what the weather was). Fridays are fun.