My big problem is that I tend to take in all the new feeds as one big chunk of text. That's what I liked about the LJ interface; you'd have all these tidbits on one long scrolling page, I could scan through quickly, middle clicking on links that looked interesting to load them into background tabs in Firefox. With SharpReader and Firefox 1.0, I can still do all the loading, but I don't have the scrolling. Instead, it's more like each item is its own email message, when what I really want is a digest.
I always liked the rendering style used by the Firefox RSS Reader Panel extension. I just did a check, and it looks like it's been replaced by an extension called Sage. This has the same side-panel interface along with an in-browser rendering of feeds. It imported the OPML file that SharpReader exported without any problems, and I was able to use the Firefox bookmark manager to rearrange everything nicely. However, it can't render multiple feeds together on one page, and it doesn't indicate when a folder contains feeds with new items. Fortunately, a lot of my ideas are already represented in the Sage Wiki, and they've even got some that I'd not considered.
One final pointer: Robert Scoble led a discussion at Bloggercon III last week about information overload. My aggregator explorations were prompted listening to the talk yesterday; I'm also starting to think seriously about how all this information flow can be channeled into a device like your smartphone.