A new startup called RSS Mixer allows you to combine several RSS feeds from different websites into one, so that you have just one fat feed of updates. Creating mixes is easy; just get the individual feed URLs, add them and click "Mix it". The resulting feed can be read in any feed reader just like any other feed. It's also available as a webpage, mobile formatted page, as an Apple dashboard widget, Yahoo! widget, Vista widget, Google gadget for Google homepage or embedded into your blog or website.
The Mix can then be shared with other users and anybody can subscribe to it. RSS Mixer is also a searchable directory allowing you to search for Mixes created by other users. If you get a Mix you like, you can extend it by adding more feeds to it creating another Mix. RSS Mixer already has quite a lot of handy Mixes like the iPhone Topsites, Political news, Apple news, Gadget news etc.