RSS feeds are great for keeping track of what you have and haven't read on your favourite sites, but seeing just the text in a box is a little plain. NewsBlur keeps track of what you read from the actual site itself.
To get started with NewsBlur, you can start adding feeds or import an OPML file from your current feed reader. You can also import your Google Reader subscriptions at any time. Then, you can browse feeds in the usual three-pane interface, but you can switch between a feed view (similar to most feed readers, where plain text and images are displayed) and the original view, which scrolls through the actual site, marking which articles you read as you go. It's pretty neat if you prefer to see the actual blogs you visit, and especially useful if you like to see comments and take part in them. It also has a pretty neat AI that will filter and highlight stories you're most likely to enjoy, which is handy if you don't feel like sifting through hundreds of articles a day (which can get overwhelming quickly).
NewsBlur is free for up to 64 feeds. You can purchase a yearly subscription for $US12 a month, which includes unlimited feeds, more frequent refreshes and a few other features. If you import an OPML into the free version with more than 64 feeds, you have the option to let it intelligently choose your favourite 64 feeds to import, which is pretty nice. Hit the link to check it out.