Before the Chicago Marathon 2009, I bought a pair of gloves in anticipation of the cold morning. I was glad I did. When my hands get really cold, it makes it unbearable to focus! I purchased a pair of Nikes Womens Lightweight Running Gloves (Style FC0113090) for $20. They keep my fingers warm but also allow ventilation and the sweat does not soak the gloves. With regular fleece gloves, my hands can get really heated and I need to take my gloves off to air them out for a bit. Though I love my nike gloves, I will wear fleece gloves for the really cold days.
They may seem like an expensive pair of gloves, but well worth it!