I use Google Reader. GR gets the job done, but it is a little quirky. The biggest draw back is that if you don't read all the new messages in a group or folder, you have to go back through and read the "older" new messages to get to the unread new messages. Putting less feeds in more folders lets you check a small amount of new feeds, but if you have a folder with many new messages you usually can't read all the messages in a group at one time.
Anyone have a better RSS reader than GR? Is there an active Usenet group that discusses RSS?