kickstand

While not for the cyclist who meticulously cares about ever single ounce added to their bike - kickstands seem like the best extra chuck of metal you could add to your [commuter] bike other then a basket or rear rack, chain guard and bell. They keep your bike up right even once you've loaded your baskets or panniers. Beautiful.

Here are a few that offer two legs, giving way more stability then just one...

Rivendell's Pletscher Twin-Legger Kickstand is Swiss made, cast aluminum, and has two legs which opens simultaneously.

Esge / SKS Double Leg Bicycle Kickstand for heavily loaded bikes, tandems, recumbents, etc. Double leg design lifts entire back end of bike up for a stable support and flips up under the rear chainstay like a standard kickstand.

M-Wave Steel Double Leg Side Bicycle Kickstand weighs in at 1.8 pounds, fits 26-28" bikes, is height adjustable, and has anti-slide feet.

Axle Kickstand 26" Wheel Bike Bicycle traditional style kickstand which mounts to axle of a 26" rear wheel. Heavy duty, easy to install and mounts to your rear axle. For single speed bikes only (can not be mounted to a bike that has speeds because of the derailleur).

Dahon's Doublestand Kickstand is center mounted. It is part of their 'Premium Component Group' and comes on their most expensive models. Might not be available on it's own.