I’m a big fan of RSS Aggregators, but I’m having the same problem with them that I had with POP mail: if I’m using more than one machine, they can’t share data.
Someone needs to build a system that lets you store your OPML file and the “read status” of each feed/post online. This would also require buy-in from the major aggregators to support this service.
Either that, or a really good web-based aggregator with a nice rich interface needs to show up soon. I’ve been tempted to try to build one on several occasions but managed to stop myself. If someone out there is planning to build one, I’d be willing to help out on the interface.