Joel linked to this thread on the topic of web-based aggregators and discussed one specific reason why he's not sure he's ready for the switch.  My  primary reason for using Newsgator online is that it is online...as close as the next browser.  I don't do a lot of cool stuff though but it works for me.

The reason he mentioned that he doesn't think he'll switch to online is that he likes to flag articles as he's reading them so he can come back later.  I do the same thing and I can do it with Newsgator.

When I'm reading feeds, I always keep one eye open for stories to use in the next RossCode Weekly, and I flag them for later using Outlook's flags. I've also used FeedDemon, and it has the same flagging type capabilities. From what I can see, Newsgator Online (or the others) don't offer that same ability - I'm not talking tags - I'm talking about being able to use private follow ups that I can go back and look at later.

Well, Newsgator online does provide that but in the way of folders.  There are two primary folders "My Clippings" and "My Feeds".  "My Clippings" is the one where you can save off articles to keep and read later or just to "flag" as something you want to keep track of.

When reading an article there is a little icon and you use that to save it to your clippings.  If you have multiple folders a context menu pops up with your list of folders.  Select it and now it's saved in your folder. 

There is an "Organize Folders" area that you use to add/update/delete folders and move your feeds around in them.  Anywho, that's my two cents worth on the topic.  No, I don't really have a “RCW” folder - it was for demo purposes only.  :-)