Usability 
KeyToss describes itself as a "Powerful, personalizable portal for smartphones". I think that's a pretty good description. The default KeyToss home page shows has a search box offering a choice of search engines, current weather forecast, recent sports scores, stock quotes, a section of news headlines and about 20 well chosen links to frequently used information like movie show times and flight status.
KeyToss is highly customizable. without even registering, users can change their location and favorite teams, choose which mobile links and search engines are displayed and add content from a list of 40 preselected RSS feeds. These changes are saved with a cookie. Registered users can make further customizations like adding pages and choosing from over 600 feeds on KeyToss' full web site. You can customize how each feed is displayed including whether to display summaries or just headlines, the number of items to show and whether external content should be transcoded. The choice of feeds does seems to be limited to the 600 preselected ones. Although KeyToss says "Is there a website or blog that you'd like to see? If it has an RSS or Atom news feed, you can add it yourself", I could not find any way to add arbitrary feeds.
Something that makes KeyToss unique among mobile portals is that it acts as a location broker. When you access some sites through the KeyToss portal, your current location is passed to the site. It's not GPS, you do have to set your location manually in KeyToss, and it's only grandular down to the city name for international locations or zip code for US ones, but is a real timesaver to not have to enter your location on Google Local, Yelp or jWire's WiFi finder. I'd like to see KeyToss integrate this functionality with Yahoo's FireEagle, which when combined with Navizon, can pass GPS or cell tower location through an API. More...