Tagging! If only! That's one of the features I've long wanted, a one-to-many relationship between feeds and categories, as opposed to the inverse we get with folders. What if I want to categorize something as "must read" in addition to "technology"? What you describe here is a useful trick, but it means I'm stuck labeling my feeds in a manner directly related to my need to be able to mark-as-read.
Ahh, I forgot that tagging is item by item, but feeds are folder by folder only. My apologies. I'll go make a feature request for it. It seems odd that they wouldn't already have this.
Google Reader's folders do allow for tag-like multiple categorization. If you use drag and drop then it acts like folders (and removes the feed from its previous location), but if you use the "Feed settings" dropdown in the blue bar you can check multiple folders and the feed will appear in all of them.
You can also turn off display of unread counts with the menu under the little downward triangle in the left column. These features are pretty undiscoverable, but they're there.
