I have been looking for a good online feed aggregator for some time. It is not at all clear to me why most of the feed aggregators out there meet my needs so poorly. I do feel fairly specific about what I want (online, oldest first sorting, OPML export, exclusion of articles that I have read) but none of those features seem particularly complicated.
I tried out NewsGator Online recently and it is pretty nice. There are a few things about it that could be better but over all I think it is pretty sweet. I definitely like it better than Bloglines, which is what I have been using recently.
One of the things I really like is the slightly modified river-of-news style it uses. The modification is that you can mark stories and groups of stories as read so that they do not clutter up your view once you have read them. I find this a much more efficient, and enjoyable, than the categorized by feed approach of Bloglines and many others.
The biggest I do not like about this aggregator is that the name of the article’s source feed is displayed below the text of the article. I really prefer to know the source of an article before I read it, rather than after. The only other real complaint I have is that it is black text on a white background, which I despise (but apparently I think it is good enough for you, since I have not bothered to create nicer theme for my blog).
Over all the NewsGator Online aggregator is definitely worth a look.