I mentioned in the past that my aggregator of choice these days is NewsGator.

I use NewsGator for 2 reasons:

1. To pull all subscriptions into Exchange server and keep them in sync across machines (and via OWA), and
2. So I can leverage the new search folders in Outlook 2003.

The first set of search folders don't have any criteria - I simply use them as a way to "roll up" all the individual folders into a single folder. (The 'Reading' folders below).

I also have search folders to deal with my action items. I use the colored flags extensively here (on both e-mail and RSS folders), and each of these folders simply matches a different colored flag.

Finally, I create specific keyword folders which let me read everything on a particular topic regardless of how I've categorized the underlying feed. The topics on this list tend to change over time based on what is relevant.

There are two limitations in Outlook that I've come across with this system...

1. There are limitations on the number of search folders

It seems you can only have up to a maximum of 20 search folders.

The limit can be updated through a registry fix which I discussed here.

2. You have little control over the organization of search folders.

The search folders are just ... there. You can't re-arrange the order. You can't organize them into various subfolders within the Search Folders root. You can't drag them into your main mailbox and treat them like 'just another folder'.

You can, of course, put them in your Favorite Folders list. This gives you some control over the order, but because you can't do any folder nesting, it basically becomes useless when you have more than 5 folders in the list.

As you can see from the screenshots above, I'm using prefixes on the names to sort the folders. It's a crude work around, but it does the trick.