Clementines always seem to pop up around this time of year where I live... I've always loved them. I'm a fan of citrus fruits, but not of peeling them. Clementines simplify things greatly, and they taste great!
On that note, I also love pomegranates, and they're reasonably priced at the moment. They're not easy to peel at all, but I find the submerged-in-water technique is the least messy (as compared to the slice-and-whack...).
Of course, while it's not a seasonal "product", so to speak, I drink a lot more cocoa once the weather cools off. Currently I am sitting here with a cup of mint cocoa with tiny marshmallows.