I have an iPhone. It is an awesome little toy. I couldn't just own one. I need a reason to play with it so I wrote an application.
It lets you gather your favorite news sources - rss/atom under one aggregation. Thus it is easy for me to gather up a number of cycling blogs and collect them under the aggregation 'Tour De France'
My favorite feature, one that is not quite done, but is coming in the next few days, is the ability to specify a tag which the system will then search for over the 'Internet World'. For example, say I am at the Ruby on Rails conference. Most conferences ask that you use a specific tag. At the rails conference it was 'RailsConf07'. Enter that tag into the tag box and igag.us will go search technorati, flickr, delicious, google blog search, etc and find entries that match the tag. This makes it very easy to keep track of the goings on at a conference via your iPhone (or computer it works there as well)
It is still early in development, but it works. Let me know what you think if you have a chance to use it.