Frank Gruber wrote a good review, published on TechCrunch, of the current state of online feed readers. This review covered just the online web based readers, not the client applications. Newsgator and some others offer both a web based reader and a client based reader. I use Newsgator Inbox which is integrated with Microsoft Outlook, which of course is client based.
Here is a list of the RSS readers reviewed in the story. Frank concludes that Bloglines and Rojo are the richest in features.
Examining traffic to my blog, the most popular readers are Bloglines (29%), Newsgator (13%), RSS Bandit (7%), MyYahoo (5%), SharpReader (5%), FeedDemon (4%), and the balance spread among a dozen or so different readers.
If you haven't tried an RSS reader I would strongly encourage you to try one of these. If you use Outlook for your email Newsgator Inbox is a great choice.