RSS readers - web based

Google Reader – In addition to tracking your feeds, Google’s popular RSS reader allows you to star items (like in Gmail), view trends in your feeds and reading habits, and recently added an option to read feeds offline.
iGoogle – Formerly known as Google Personalized Home, iGoogle allows you to include RSS feeds as part of your custom start page.
Netvibes - This personal homepage provider includes hundreds of “modules” you can add to your page from Hotmail to your Flickr photos, but also lets you create your own modules by simply entering an RSS feed URL.
Pageflakes – Another personalized homepage provider, Pageflakes functions similar to Netvibes, letting you select from pre-made modules or create your own by adding an RSS feed.
My Yahoo! – Still the most widely used custom homepage on the Web, My Yahoo now allows you to add RSS feeds alongside your weather, stock quotes, and news. Similar to Netvibes and Pageflakes, My Yahoo allows you to re-arrange your feeds with drag and drop features.
My Netscape – Netscape’s personal homepage service also includes the ability to add RSS feeds as content modules. An account also lets you participate in their Digg-like homepage voting.
Daily Rotation – A no-frills personalized homepage aimed targeted at techies, Daily Rotation includes recommended feeds from hundreds of tech sites, and also lets you add in additional feeds of your own choosing.
Rojo – A part of Six Apart, Rojo is a web-based reader that combines RSS aggregation with a community of sorts, showing what people are reading on their homepage.
Bloglines – One of the early online RSS readers, Bloglines “split screen” interface makes it easy to view the full content of any of your feeds. The service is part of the IAC family of sites.
Newsgator – NewsGator’s RSS reader allows you to organize your feeds in Windows-style folders that can be expanded and collapsed.
MySindicaat - an advanced online RSS reader with a tree-like feed layout, available in several different flavors, including a mini ticker and a mobile RSS viewer. It also has RSS mixing capabilities.
Fwicki - web based RSS reader that lets you create custom river-of-news style feeds.
NewsAlloy - a fast and full-featured web based RSS reader. Also has a mobile version.
Feeds 2.0 - a personalized RSS aggregator, that learns from your reading habits and displays relevant feeds