Since I haven't seen anyone posting about this, I suppose I will. I'm guessing not many people have it yet, but there's a new feature in Gmail called Web Clips, which displays little headlines above your inbox or message and is fed via, um, feeds.
It looks like this (click to zoom):
You can add your own feeds and/or choose from their selection. It also swaps between feed headlines and ads, which is pretty clever, cuz it gets you looking at the ads a lot more (I've found). Each is labeled, of course. Nice.