Balmy shoe covers aren't for everyone, especially when the weather doesn't warrant it. When the roads are wet, but the skies are clear, strapping on a full bootie is a recipe for hot, sweaty feet. That's why Castelli made the Toe Thingy. The Toe Thingy lets your feet breathe while protecting the front of the foot from water and wind.
Castelli's Toe Thingy is made from durable neoprene fabric. This material not only provides insulating warmth, but it also blocks water and wind on the most sensitive part of the foot—the toes. The Toe Thingy is secured to the shoe by an aperture that encompasses the cleat, and to resist rips, tears, and general wear, Castelli included a silicone print on the Toe Thingy's underside. For versatility, Castelli recommends using the cover alone on mild days, and as a layer between your shoe and full shoe cover during nasty weather.
The Castelli Toe Thingy is available in one size, and in the color Black.
If you go hardcore into cycling, you realize the value of all the specialized bits of apparel. There are shoe covers for every occasion: speed, rain, cold, and cold and rain. The good ones, alas, don't come cheap. But there are alternatives that, while not necessarily ideal for all conditions, can help. That's where the toe thingy comes in.
If the road is wet or you're riding in a drizzle it'll do a good job keeping the leading edge of your foot dry, which is where you really feel the discomfort. The warming benefits seem to me to be fairly minimal given the amount of ventilation that my cycling shoe has, but the toe thingy delays the onset of cold feet a fair bit in temps down to the 40s (but really these are designed for milder temps). Where the toe thingy really shines is convenience. Unlike your typical shoe cover, it's a cinch to put on and you won't wear out any zippers or tear the neoprene on the ground walking around. Plus it doesn't cost much!