I'm becoming resigned to the fact cold weather is here to stay for a while, so I've gone through the annual ritual of putting away one set of clothes and getting out the layers. One new layer I'm liking a lot is this Hot Chilly Zip-T.
It is designed to be a base layer for skiing, with a form-hugging fit. But it also works well for cool-weather running or biking. It basically functions like a heavy-duty fleece, but is slick on the outside, fuzzy on the inside. That's a good thing if you're piling on layers or trying to be aerodynamic on the slopes or on a bike.
The Hot Chilly Peachskins zip T is deceptively warm and is quite comfortable as something to wear down the block on a fall day. My only beef with it is it is designed to be zipped up all the way on your neck, so the collar doesn't quite know what to do with itself if you're unzipped. For something you're just using as a base layer, the simpler banded crew might be better (but is only a buck less - $34).
These come in six colors and Hot Chillys also makes a whole line of base layer tops, bottoms, and socks for men and women. You can find them at various retail outlets or ski shops like Sun & Ski Sports or Finish Line. Or go to the Hot Chillys site to find a local retailer.