Update! I forgot to mention that you can get access to the ClearContext beta by using the invite code webware on the ClearContext site.
On Monday, ClearContext, which has had a paid, enterprise-level e-mail organizer for a while now (download), is releasing ClearContext Personal, a free, de-featured version of the product (download). ClearContext isn't Webware, but since I've covered Xobni here, I'd be remiss to ignore it.
CEO Deva Hazarika acknowledged to me that ClearContext Personal might not fit the needs of someone like myself, who gets a lot e-mail that's important but comes from strangers. I tried it anyway.
ClearContext Personal organizes your e-mail as it arrives, in contrast to Xobni, which helps you understand more about the people who send you messages. I think ClearContext Personal is a more useful tool, but it's also harder to get into, and if you've already got your workflow in Outlook set up in a way you like it, you may be frustrated when ClearContext tries to re-write your rules.
ClearContext examines your e-mail behavior to determine which senders are most important to you, and it color-codes (and optionally sorts) your in-box by priority. I found it did a middling job of determining who matters to me. You can easily train the app, though. I didn't bother, which meant I really couldn't trust the color coding.
The app understands message threads and, in each message window, will show you a list of other messages in the threads; it can even clump messages in a thread together in your in-box. ClearContext lets you "unsubscribe" from threads you don't want to be bothered with. It's great for putting down spam-like threads from your co-workers. It can also automatically collect all your notification e-mails ("Bacn") into folders, and similarly can auto-file all the messages you don't want to keep but are afraid to delete in case you need them later.
If you're an e-mail filer, ClearContext makes it much, much easier to move messages from your in-box to their final location.
The free version of the app has some limits on the number of Outlook files it can support, and it lacks the pro version's delegation features. Another issue for power users will be ClearContext's lack of support for mobile devices or for users of multiple PCs. And there's no online version of it.
ClearContext is not nearly as pretty as Xobni, nor is it as easy to use. (I didn't like having an interface split between a new menu and a dedicated toolbar.) But it's a more powerful tool for organizing your in-box. If you can play by its rules, it could save you time.
There's a short video on the product. The company is working on a version for Gmail.
See also: Xoopit.